well, ideally all of the wrenching should have been done before the race and during the race at the pits it's mostly just filling up gas, hydration, check oil/fluids, but with desert races you never know what's going to happen. it's common to break stufff that needs to be replaced with a spare (if you have it), i.e. wheels, handlebars, brakes, etc... probably a similar story for UTV, Trucks and others. when something breaks, it's sometimes nice to have extra hands.
the silver state 150 and the desert challenge are really short races and won't have many pit stops. however, it's good to go anyway network and meet people/teams. how long will you be in the states ? if you are around for Baja1000 you might see if you can get hooked up with a team somehow before then. this year's Baja1000 is point to point, in which case teams need more crew/support people then during a loop year. check some of the websites I listed for their schedule of races, to see whether there are other races to go to.
amateur teams are more likely to need some help/people, while pro teams have it pretty much figured out and it would be hard to get in to help. you might try with the Class 11 teams, they are typically on a budget and some could probably use all the help they can. I know Class 11 isn't trophy trucks, but it's pretty cool none the less. it would be rare to get a ride along offer in the race.
you might also try to volunteer to help at a BITD or SCORE event. I don't know what the process is to get in, but chances are if you are part of the recovery crew, you will get to practice some trail side mechanics to help get vehicles out. it woudl be a good behind the scenes learning experience.
Thanks for your reply.
Please do not undestand me wrong, i dont want to steal time. We really want to help a few days not only a few hours.
I dont know it yet, if i have time. I am helping a friend I met on the burning man at his artcar. I let you know in the next days.
.