I got challenged to try to keep up with a wrangler in the sand dunes this weekend and I got no experience driving in the sand with my new to me 91. I am running bfg at 35's with 4.88's and a detroit in the rear. I plan on airing down to 15-20 psi. I am wondering if I should be in 4 hi or 4 lo. If 4 hi do I want to engage my cdl. I don't want to be made a fool by a jeep lol. He is running 37's mt's with lockers. I expect there to be a fair amount of hill climbing on the trip. any tips or advice will be appreciated, thanks