The owner manual is ultra-conservative, I think. The genset gets plenty warm in even 30 minutes at half load, and I find it hard to believe it takes two hours to drive out moisture unless it is in a swamp. One a/c is probably no more than 25% load, though. We are talking maybe 1400-1500 watts for one a/c on a genset that is at least 4000W and maybe 5500-7000 (gas) or even more if diesel.
Typically the manufacturer's engineers recommend a procedure that works even in the worst case scenario, by the dumbest owner., and they do not care if you waste fuel or a lot of your time, or have to drive the RV out into the open to do it. They are just doing their best "CYA".
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL