Yeah - like he said . . ..
Most of the tracks I know of either have no RV electric hookups, or they tend to be inadequate.
Propane generators use ~1 gal/hr at moderate load. Most RV's have a propane tank somewhere in the 40 gallon range - of which only ~80% is usable (dunn'o why). So - even at moderate load, you'll get about 30 hours of generator use from a tank of propane. And when you're out of propane, NOTHING works - refrigerator, stove, electricity, hot water, nothing. A friend of mine who is a racer and is part owner of an RV dealership tested an RV with a propane generator (on their lot) just for grins. The result: with A/C and normal stuff running it ran out of fuel in 32 hours. That's an awfully short track weekend!
If OTOH, you have a diesel generator that uses ~.75 gal/hr and a 75 gallon capacity, it's more than good for a weekend at the track. Also, in HOT weather, you'll probably be running the generator while you're on the road. The dash air just can't cool a motorhome in >90* weather, so you end up using the roof air units.
FWIW, my motorhome has a 75 gallon diesel tank. On a typical Gateway trip, I normally refuel at Sikeston, MO, run the generator all the way up, camp for ~50 hours, run the generator all the way back, and refuel at Sikeston - total use for ~300 miles and ~55 hours' generator use is about ~55 gallons. Most (if not all) RV generator fuel pickups are situated at like 80% of tank capacity - so even if you run the generator out of fuel, you still have 50 - 100 miles of fuel left to get back to a station.