One of us must be a clown here, and if we know "Charles's Law", then we don't know much about the airplanes...not even about a full car-fuel tanks...
Don't worry, I know about both, and I understand with increased pressure you have the tank venting it, I wasn't suggesting you would have a complete catastrophe or anything of the sort.
In essence the idea is akin to a giant toaster, It just seems that it is using a sledgehammer to crack a walnut. If overnight conditions are conducive to frost, but >0 temperatures are expected by departure and frost is expected, then just throw a thin insulating sheet over the wings the night before, that is teathered down. Then anti-ice it properly the next day.