I thought I would finish this up before I totally forgot what I was going to say. If you missed it, part 1 is here.
I am not sure about the best way to approach this so that it will tie together in the end... so I am just going to make a big list of things that may be useful to anyone thinking about doing this.
1. You cannot legally park most places. Apparently "normal" people don't like homeless people, and tend to get laws passed in order that those they don't like looking at or thinking about will go somewhere else. For this reason you cannot park on the street, in an empty parking lot, or basically anywhere that is not going to try to charge you a lot of money. This even extends to private property where you have been given permission by the owner. My original though was that I would find someone with an empty yard that would be willing to let me park there for $100 a month or so. While this is possible, it is still technically illegal.
2. Campgrounds are not inexpensive. In Little Rock, AR there are a number of rv-parks, and campgrounds both private and government. For a crappy looking rv-spot with water and electric in an industrial section on the outskirts of Little Rock it was $400/mo. For a camping spot in a state park it was about $30/night or $600/mo. For this you can get a pretty nice apartment fairly easily. There may be cheaper options, but I was not able to find them, I even considered renting a mini-storage and just staying there.
3. Some businesses allow RV's to park in their lots overnight. These include Walmart and Cabellas and maybe others. They do this because people traveling in RV's have money and buy stuff in their stores. So they want you to have an actual recognizable RV, not a slightly modified truck. They also do not want you to do this for more than a few days at a time.
Basically, if you decide to do this you need to understand that if people notice they will generally disapprove. They will likely not care if you are trying to pay off debt or save money, they already have a long list of prejudices that they will apply to you. This means you will probably have to be sneaky and willing to be a little legally ambiguous. You might get harassed, you might get fined. I doubt much else would happen.
My solution was just to drive around in a wilderness area about 20 miles away and find fishing ramps. Some of them had fire rings so people occasionally camped there. Fishermen show up at 4am and can also be out late, so a car parked by a fishing dock will generally be assumed to belong to a fisherman somewhere nearby. I found 5 different spots and rotated among them so I was not in the same place every night. In the two years I was there, I was never questioned. A couple of times people in 4wd trucks came through making a lot of noise but that was about it.
Other options would be to just buy a piece of land. If you have the money it is at least a pretty good investment. Some people sleep in motel parking lots, hospital parking lots, 24 hour grocery stores, anywhere they won't be noticed. This is definitely not legal, but if you are sneaky about it and don't stay at the same place more than one night in a row, you can probably get away with it for a long time. If you get caught you would likely get a warning or at worst a small fine.
One suggestion if you have a van is to make it look like a commercial vehicle, even disguise it with ladders and signs to make it blend in. Then you can probably park behind stores as long as nobody notices you parking and not getting out. Get there late, and leave early.
4. You will need a fitness center membership. These are usually about $30-$50/mo. But will give you a place to shower which is fairly important if you are working. I usually would just hang around a coffee shop or book store after work. You will probably find yourself with a lot of time to kill so find some places to go when you have nothing better to do.
5. Winter - I actually prefer the winter, it is easier for me to deal with cold than heat. I had a good down sleeping bag from hiking the AT , and at least in AR I was easily warm enough in the winter. The car was usually warm by the time I parked, so I just had to get into bed within a few minutes and all was well. It is important to have some kind of insulating mattress in the winter. A normal mattress would be fine, I used a thermarest car camping mat. Which is basically a very durable air-mattress.
6. Summer - Summer is a little more complicated. It gets very hot and humid here in Arkansas and I don't do well with that. I experimented with a number of ideas in order to stay cool without AC. Most of them did not work, so I will just talk about what I ended up with that did work. Basically, since I was not trying to be especially sneaky I kept a window down in the summer. I got a piece of fine netting to keep the bugs out, and tied some coins in the corners to weight it down. I would throw this over the door before I closed it so that it would hang on the outside and cover the window. I then got six computer fans (the type they put in the power supply), tied them together with zip ties at the corners added a power switch and hung the whole thing from a string so that it was in front of the window about 1ft from me when I was sleeping. The idea here is that they are very low power (about 0.05 amps each) so they can run all night on the car battery without draining it. They are also very quiet and durable. This was probably the single biggest factor to being comfortable in the summer. It also had the added benefit of killing all the mosquitoes that managed to get in while I was closing the door. I have the finished fan packed away at the moment... I will dig it out and take a picture if anyone is interested.
The final step worked great until it broke. Basically I got a cheap backpacking style tube air mattress and filled it with water. This ended up being about 200lbs of water much to my surprise (the one I used was a lot lower quality than the thermarest I linked to but basically the same idea). The idea was that while the fan kept the top of me cool, the bottom was still well insulated and hot on a mattress. Some people seem to be able to get a cot inside to compensate for this. Having a thin piece of cloth under you is a lot cooler than a heavy mattress. I did not have enough room for a cot though, so I thought I would make a water-bed with cool water under me. If it was especially hot I would freeze (at work) a couple of two-liter plastic soda bottles full of water and put them under the water-mattress after work to cool it down. That way it would be cool by the time I went to bed. This worked really well until the mattress started leaking a few months later. I am not sure why it started, but once it did it was leaking all over. I think I would try to fill it with a non-organic water based gel if I do it again. It may have just been a low quality pad. By the time it was leaking though, the worst of the summer was over.
I think that about covers the basics. I am not sure how much interest there is in this so feel free to ask questions in the comments.