Is there any way you can rent out a generator to power the filters and heaters in your tank?
If not, you can (as discussed in a thread previously today...take a look ) wrap up your filter to keep it warm, dont feed your fish to reduce any waste that the fish may produce, if you have access to a battery powered air filter, use it to keep the water oxygenated. Wrap up the tank to keep the water there warm. People have suggested blankets but I think a bed cover would be better....keeps you warm at night so your fish will be warm!
Thats my limited knowledge, copyright of all those on this forum!!