I have seen it done, mostly on bus conversions and some older TTs.
I am assuming your roof top AC is dead and you are installing the mini-split as a replacement. From a power perspective it is very straight forwards. It needs a 120V, 20 amp or less mini split. Disconnect the old roof top AC power line from the circuit breaker and and connect your new Mini-Split wires. From a power perspective that is about it, as long as you have a proper auto transfer switch for your onboard generator, properly sized circuit breaker and wire. For a house, there is some code requirements for wires that exit the structure. Not sure RVs have the same rules. But then do RV's really have any code enforcement????? no but any ac wiring needs to be done to code. NEC article 551.
Big issue is making sure to properly braze the new copper refrigeration lines as they have some strict purity requirements.
Let us know how it turns out.