Since you're replacing your failed unit with a "household" unit, were it me, I'd "try it" before I installed it.
To "try it" means two ways - shore power and genset power.
First, put the A/C on a table, plug it into house power (i.e., the same as shore power) and confirm that the A/C works as you expect.
If it does, then unplug your "B" from shore power, if it's plugged in; start your genset and plug your "new" A/C into an available outlet on your "B"; and turn on your A/C and confirm that it works. If it starts, you likely won't need a "hard start" capacitor. If it doesn't, then putting one in line will likely be required. If it does require a capacitor, then you'll know as your genset will conk out trying to start the A/C. It'll begin to start it, in all likelihood, but won't quite make it and die.
Turn the A/C off, restart the genset, and try the A/C again. If the same result, then you'll know.
While your "new" A/C is a different BTU capacity than your failed one, if your failed A/C's hard start capacitor is outside the unit, then you may be able to reuse it - I'd talk with Roadtrek about that. If you can't reuse it, while they may not tell you what your "new" unit requires, they may tell you what the specs are/were for the capacitor on the failed unit. The two will be similar I'd bet. Not identical maybe, but similar.
A little testing and a little homework may get you a solution.
Cheers.