I don't think marine tanks would be that bad if you're smart about it. Keep the lights off or only minimal lighting, everything should be fine for a couple days. You could probably cut back on the pumps a bit too, though most powerheads would use minimal amounts of power.
With the cheapies for an emergency you'd need to remember to start them occasionally. Run it for 5 minutes every month or so. Otherwise it probably won't start when you need it.