If you are using the slow, blushless (635/556) mixture then after 16 hours in the mid 60's it will just be barely hard...if that. This is some slow epoxy which likes heat. I have no qualms about waiting 3 or 4 days to recoat at these temperatures with this epoxy...though I usually try to recoat the next day. I also never sand between fill coats...except when I'm down to the last one or two...and then I let them cure quite awhile before sanding. I scrape the runs, etc., with a carbide scraper, hit it with a green pad, and recoat. I wipe down with a dry cloth unless I've been sanding...then I use a wet cloth. I've never used soap with this epoxy....just the green...or purple pad...between coats. Your temperature scenario is just about the same as mine today...and I applied some fiberglass to a pirogue just before I came to work. It will be ready for me to go to another step on that boat tomorrow.