I am interested and not too far from the park, in Midland.
I was there in June and have been going to Big Bend for 20+ years. I can help with planning if you are interested.
As far as camping inside the park, Cottonwood and Rio Grande Village are both near 4x4 trailheads and can accommodate groups. The Chisos basin can also accommodate groups but is not near the trailhead. As note before, the Primitive Roadside Campsites can be pretty limited on number of vehicles, but a few can handle 2+ vehicles.
I was there in June and have been going to Big Bend for 20+ years. I can help with planning if you are interested.
As far as camping inside the park, Cottonwood and Rio Grande Village are both near 4x4 trailheads and can accommodate groups. The Chisos basin can also accommodate groups but is not near the trailhead. As note before, the Primitive Roadside Campsites can be pretty limited on number of vehicles, but a few can handle 2+ vehicles.