As a 24 year old with $50,000+ of student loans to pay off I lived out of my 1977 ford. E-150 for about a year and a half. Granted I work in the film industry so while I worked I could park at the circus and depending on the transportation department I had free electrical hookup, free water, free propane and when that one kicked the bucket and I upgraded to one with black/grey water they helped with that too.
It might be because I live I'm Canada but I was able to find a few parks here and there with van communities. A few times I parked in neighbourhoods with no restriction parking and had a few people approach me but they were normally very nice.
As for showers, YMCAs, truck stops. Couchsurfing.com is a great site to meet people and find driveways to park in (depending on how outgoing you are, cook them a dinner and you will have access to their shower).
I did get pneumonia one winter from the cold but looking back it was from other factors as well but unless you have some sort of heater I would not recommend boondocking without a good sleeping bag. I used to be in scouts, we used to camp in the snow all the time, with the right gear you can absolutely survive. You just have to be smart. http://www.mec.ca/AST/ContentPrimary/Learn/SleepingBags/IntroToSleepingBags/SleepingBagSystems.jsp
I taped duvetine onto my windows behind my curtains so I could have all the lights on inside and from the outside it looked like no one was inside.
The days of my stealth camping was a lot of fun, one big adventure which led to many new friends and inspiration.
Remember police aren't out to get you, just don't overstay your welcome, don't be selfish and if you get caught admit your mistakes.
Good luck