Keys on foot
Bonefishing in the keys is hard, add no boat to the mix and it gets even tougher. People do get them though. Try Ann's Beach, pretty spot. Not hard to find. Also Long Key State park is good at times.
For real thrills and the possibility of tying into a big fish, try fishing the bridges at night. Check out the Channel Two bridge, you can walk along the concrete bulheads along the side and flycast. Rig with 80 pound shock tippet. Bring a stripping basket. Cast streamers on the Gulf side on the outgoing tide at night. The later the better. Tarpon.
For camping, check out the KOA at Fiesta Key. You can reserve right on the web at koa's site. It's a nice spot.
I am sure you will get plenty more suggestions too.