Parks or forests with dispersed camping within a 3 hour drive?

Howdy! My friends and I are looking for dispersed camping spots within a 3 hour drive of Houston. As in, parks that allow you to hike in and find and set up your own camping spot. We recently went to Big Thicket National Preserve for “backcountry” hiking. Looking for something similar. I’m only able to find parks with designated camping spots (“primitive”). Thanks in advance!