Check the circuit breaker that powers your second AC. It should have its own breaker and if you have an empty location for an additional circuit breaker, it is an easy upgrade.
The water leaking is a bad thing and I'd suggest to do an interior pressurized test to uncover any leaking locations.
Your floor is probably a composite panel construction. Since it is comprised as a foam "sandwich", there is probably little you can do to make it completely stable. A heavy mat or upgrading from vinyl to plank composite construction will offer a stiffer floor.
Good luck with your new RV. Hoping you can work out the bugs so that camping doesn't become a maintenance event.
