I lost mine for the same time, probably the same problem. Running anything off of a car battery inverter is not anoption when the temp is plummeting and 22 inches of snow is being dumped on us. I used my computers UPS reserve batteries to power my air pumps by cycling through my tanks-10 min. wait 5, 10 min the next tank, wait 5, 10 the next tank and so on until I ran out of power. I use a combination of air driven sponge filters and an HOB in all of my tanks. If you have a removeable wheel in the HOB, moving it to the tank is a great idea. Do everything to keep your biofilter from dying off.
By the time my power was restored at 4:45am my house was down to the low 60's and my water was also. I didn't do water changes since my heater is in my garage and adding cold water would not be good. Keeping up with water changes by heating water on my stove (lighting burners with a match) would be more than I could maintain with no sleep.
Insulating the tanks with blankets is good. Try to keep your fish in a low metabolism mode as long as possible.
My biggest questions were related to what to do when the power is restored. 60 degree air seems not a good idea to be pumped into my tanks. Should heaters be unplugged until ambient air reheats the tanks to the low 70's?
Finally, I have not lost any fish and hope you didn't either. I have 4 tanks of tangs and keep looking for stress related diseases, infections, etc. and so far OK. My 5 week old N. helianthus fry and even younger J. transcriptus fry seem to be fine.