I was in my hometown a few months ago. We elected to stealth camp on the less touristy north side of the island in a construction area simply leaving early and arriving late. There is very little undeveloped space and the beaches are patrolled but you can score cold showers there. There is an incredible, well priced vegetarian restaurant about half way down Duvall St. and the libary offers free internet. If you’re willing the islands above Key West are just as pretty and have far fewer tourist. You could stealth on one of those and go into town during the day. There is a youth hostel in town but getting in may be tough. Definitely look up Goof, he’s a crazy mo-fo. The number one goal of Key West if you’re a tourist is to get money out of your pocket. It can be done on the cheap but you will have to use a few thru-hiker tricks!
E-me if you want any more info.
Puck
Puck