you don't mention what model generac you took out of your RV, but hopefully the Onan 4000 Microquiet will fit in the available space.
The Onan has 1 30amp circuit breaker, so that is probably smaller than the Generac. It will easily run one ac unit plus charger/converter.
If you run microwave or hair dryer, you may have to practice some energy management (turn off ac unit!) And you will probably have to extend battery cables, fuel line, a.c. wiring, as all Generac hookups are on right side as you are looking at generator, Onan hookups on left side.
Onan has an optional hanger mount bracket that might help with the installation. Good luck with your project.