The water in the waterheater is not going to turn cold in an hour. Even overnight, provided it is not really cold, the water will be plenty warm enough for a shower. The mixer setting will have to be more towards HOT thats all.
Hot water is a non issue anyway. The propane will warm it up enough from stone cold in 15 minutes.
As far as 120AC power goes, having a decent sized battery bank & inverter really are handy for a Wally overnight. No, you can't have A/C but you can have your TV, your phone charger, maybe even your toaster or coffeemaker without even thinking generator.