Nuisance GFCI tripping, need advice on how to fix
I recently installed a 15A GFCI in the first outlet from the entrance panel on a basement circuit that powers 5 wall outlets and 3 ceiling light fixtures that use the new CF bulbs. The maximum current on that circuit is never over about 6 or 7 amps according to my calculations. One light fixture is on a 14awg wire running off of another fixture, so even though most of the circuit is 12awg wire I used a 15A GFCI and installed a 15A breaker in the main panel because of that 14awg section of wire which would be very difficult to replace with heavier wire.
OK, that's the wiring set up, here's my problem. I am getting way too many GFCI nuisance trips, especially during thunder storms, which of course knocks out the entire circuit. That wouldn't be a major problem except that one of the outlets powers a small 7 cubic foot freezer which needs to be kept running. I want to spend some time with my son and his family in another city this summer, but I am afraid to leave home for any long period of time because if the GFCI trips while I'm away for a few days the freezer will be off and a lot of expensive meat will spoil. Would installing a GFCI breaker in the main panel in place of the normal breaker for that circuit help the nuisance tripping situation, or would replacing all of the regular receptacles on the circuit with GFCIs work better? I want to have the basement receptacles GFCI protected according to NEC code, but I also need to have them reliable.
Another idea had crossed my mind at first, but I don't know if it would work. If I replaced the 14awg section on the circuit with 12 awg wire and then replaced the 15A GFCI with a 20A would that reduce the nuisance tripping? Replacing that section of wire would be difficult but not impossible. If there is no quick and easy fix to the tripping problem, when I leave home I may have to leave the freezer plugged into my heavy duty 50 foot 12awg extension cord that I would plug into a 20A receptacle on the main floor of the house. I know that isn't advisable according to what I read in the Wiring Simplified book, but it may be the best I will be able to do under the circumstances..