On advice ...
Just to stop others making money out of my fabulous (good word?) idea:
Suggestions - published so that they are freely available, not patented:
Refuel the tank to be used for climb out with warmed fuel, so that the water build up can be purged before it freezes. This will also prevent legacy build up from previous flights. It might even thaw legacy frozen muck so that maintenance can drain it off before engine start.
Lag the tank so that it stays warm.
Warm tanks in flight so that the water purge works in the cruise, instead of leaving it to the warmer descent phase.
Disable the fuel purge from at least one side before you are committed to needing power to make the field.