GK, I once saw deep cycle batteries at West Marine that were sealed, used an unusual chemical, and very much smaller than regular ones - would one of these work for the coach?
As you can tell from my battery question, I am no electrical whiz, so I cannot help w/ your inverter question. My only personal experience w/ inverters is the 750 watt little inverter we just bought at Lowes to run an oscillating fan from our boat or car battery in the event we get a hurricane that takes out power for a few nites.
In our part of town, Katrina and Rita only took out power for a day, but back in 1992 or so, the remnants of Andrew blew thru and took out power for a week - few remember that Andrew didn't just hit Homestead, FL. Andrew hit Baton Rouge with a bigger punch than Katrina or Rita, and if it had hit LA first, with the same fury as in Homestead, Baton Rouge is not too far inland to see major damage -in which case I hope our RV can take us away, or at least we can use its generator for some AC relief.
Ahh Hurricanes; hate the wind, but enjoy the drink!