camp at 2-3 races per season...all sites I stay at are completely primitive, so my advice reflects that. Adjust as needed. Not sure how it happened, but I've become our "ring leader" for trip planning. Here's what I do.
The most important things I see for my group is to keep people fed, watered (literally...dont let too much booze spoil the ability to enjoy the race), and clean.
Pre-plan and make a menu for every meal of every day, include a checklist that includes every. single. ingredient you need. Pre-make stuff that can be pre made. These lists should include cooking tools, fuel, and utensils you'll need. Nothing worse than prepping the big meal and realizing you forgot to pack something...also removes some thought process should you have enjoyed a bit too many beverages.
Teach rookies to RV'ing that you have limited water and limited tank space. Don't be afraid to get a bit preachy to a newb about conserving water, not taking 30 minute showers, etc.
And with that, pack extra water in jugs.
Make sure you have enough fuel to power generator(s)
Make sure you have methods to secure valuable items - i've never experienced a thief at a race yet, but my stuff is also locked down. Most crimes are crimes of opportunity.
Firewood, fire ring, and method for starting a fire...as well as some dedicated quenching water
Water - bring extra...did i mention that already?
Depending on the size of your party coolers and ice will help. The RV fridge doesn't cool beverages fast enough for a large party (we have 16 people in 3 campers usually). Fridges hold the food. Coolers hold the drinks.
Pack advil
An extra canopy or two are worth their weight in gold
Wash dishes outside to save on tank space in the rig (less important if the rig has a dedicated gray tank for sink only, but if it shares space with shower water do it outside)
I think thats it :-)