Short-course and desert racing are two completely different animals. Setup is different, how you prepare for the race is different, the budget is WAY different, and how you approach and drive throughout the race is different. Short course is a sprint - you are battling other cars, and setup and tuning are everything. Desert racing is more about keeping your equipment at 100% while going as fast as you can in the dust and not making any mistakes that will cost you. Logistically, you will need pit support, chase trucks, a good co-driver, a good radio setup, a crew and a plan. I would suggest looking up the rules of whatever race series you want to race in, because usually there are a lot more tech and safety requirements for desert racing than short-course as well. The good news is.....the best way to learn is to talk to some desert racers, build vehicle to go race in, and go do it. Experience is a great teacher, and if you race a smart, clean, problem free race your chances at a top 10 finish in the UTV classes is usually pretty good. I started desert racing years ago with a loop race - the Parker 250. That way I didn't need to invest in the chase stuff......I just needed someone at the remote pit with gas can (did great that year, too)! Local desert races (loop races) are also a great place to get your feet wet.
We did race the Vegas to Reno a couple years ago with just one chase truck - it was difficult because that truck had to race us to every pit, and sometimes they missed us. Two is a minimum I'd say to be able to make all of your pits. Exciting though!
Anyway, this topic is way to big to cover on a post on a forum.....go to some races, talk to some racers, read through your rulebook of choice, and have at it!