i would consider warming up the shop above ideal temp and then shutting off the heat a hour before you want to varnish if you can do that without the temp dropping too fast. i agree with others, a quicker drying coat (even a thinned version of your current varnish) should get you set up quickly. careful sand, wipe (maybe with mineral spirits?) then tack cloth. good look, looking very nice.
Dick R., East Glenville, NY
49 F-1: Flatrod II (flat motor, flat paint)
Keeping one more flathead alive
It smoked, but gave it up 7/27/2013