The size hassle comes mostly from starting the air cond unit.
When 2 AC attempt to start at the same time , the amps required get ugly!
At start the AC may require 3x the running load , there are simple solutions , mostly from the RV folks.
One is a timer not always built into the AC that re quires about 3 min between the time the unit shuts down and is allowed to restart. This gives time for the head pressure to bleed down.
Second is a device that only allows one AC unit to start at a time , waiting a couple of min before allowing a second unit to operate.
You might consider using the noisemaker cooling circuit to heat the boats HW heater, as the noisemaker maybe on more than the propulsion engine on a cruise.
Load shedding is almost invisible if done right.
The second air cond going on might turn off an electric water heater , which may not be noticed.