>>590048i don't understand how the guys downtown walk around in suits without dripping in sweat. when i walk around downtown houston for 2 blocks in the summer i'm sweating. the fucking humidity is brutal.
as for your question, OP, texas has tons of free camping on the coast and in national and state forests. just google free campgrounds texas. east texas has the lone star trail and tons of other forests to get lost in, and they have minor hills.
the hill country is best, but unfortunately most of the camping there is state parks. gardner is really cool in the summer they have dances on the weekends and it gets lively. lost maples is a hidden gem and is gorgeous in the fall. perdenales has some pretty good primitive camping and is a 45 minute drive from downtown austin. colorado bend is pretty damned unspoiled, or atlseast was back 10 years ago the last time i was there. hill country state natural area (i think thats the name, its mainly for horse people) is pretty nice. and enchanted rock is a must, even just for a day hike up the rock. i don't really like state parks but these are some of the few i can actually recommend. all except gardner have primitive camping.
if you want to go way out there, there is big bend and guadalupe mountains. you could spend 2 weeks hiking around big bend and not get bored.