I know that I have seen & talked to alot of folks that used to work the beach from San Louis pass, Surfside,Quintana, and Brian Beach's all the way to Sargent beach with no problems or limits.. You might get a local map(Brazoria county)to find alot of the rat trails back to some of the most secluded places that you might want to try..Also all up and down the Intracoastal canal there are alot of burms (settlement Ponds) where the Army Corps of Eng pumps all of the silts and debris out of the canal,I have found a few intresting things over the years..I run across folks out in the middle of nowhere doing my thing and they are always friendly and like the company in passing.. They have started enforcing laws regarding 4wheelers and the dunes(erosion) so you might be carfull with that but there are still alot of places to ride and access... Good luck ...Mike