hello neilgeddes -
From your initial question, you do have time to spare. the next two suggestions from mm flynn and englishal I think really cover the situation nicely. As for buying antifreeze spray and gunk, that sounds like money for trouble later. Lavish use of water even in fine weather leads to corrosion.
Lucky you to have a hangar to keep the pride and joy safe.... refuel the day before, keep it full if possible (this prevents condensation accumulating in your tanks).
As for predicting frost on the wings and tail, your car in the morning will give you an idea of the problem! No hurry, you've done all the planning before you roll it out. Fog and low cloud? decide on some other activity. Cold bright sunny day, best of all. The improved performance will be a revelation.