My first choice if I had one would be a small inverter type generator (Yahama EF-1200i or Honda EU-2000i) powering my converter for at least six hours during daylight hours, Not very noisy, and I would double chain it to the RV's hitch.
Alternate is the ONAN on board with a Gen-Turi to keep exhaust fumes above the roof where they do no harm. (The Smaller portable is preferred due to fuel consumption)
A 3rd alternative, which I have used, and I like it as much as the Honda 2000 is a Genrac 1000, this is a traditional generator (not an inverter model) but enclosed so the weight, fuel consumption and sound levels compare with teh Honda 2K, but.. only 1K out, but it is a true 1K out so it will run my Progressive Dynamics 9180 at full boost mode, And has.. Too bad it grew legs and walked off.