I like the battery power supply option...
I also like the battery option. I am using a pair of 6-volt Trojan golf cart batteries in series, and float charge them at 12.8 Volts. Yes, it's not 13.8, but 12 Volts is close enough, and that last 1 watt of transmit power that I am losing really does not make any difference whatsoever. At 12.8 Volts, I only need to add water to the batteries once every 60 days or so. If I float them at 13.8 volts, they will boil out in 2 days or less.
Those golf cart batteries are extremely high current, and very deep cycle. They can keep my whole ham station going for an unknown amount of time. I do cycle them once a week by shutting off the charge supply, letting the voltage go down to about 11.8, then turning the supply back on. Under normal monitoring and light-duty transmit, running it down to under 12 Volts takes about 12-14 hours.
I also have a solar array that I can patch into the power bus if needed or desired, and a 7.5KW continuous-duty gasoline powered Generac Niagara with a whole-house Eaton transfer switch if times get really tough.