When I was on track to do my end pours, a storm with 20 deg. temps and snow hit. For that and other reasons, I did slanted end pours indoors in several stages.

I propped the low end of the kayak inside a corrugated cardboard box weighted with a paving brick on the bottom and lots of rags over and around the brick. A loveseat I had already turned onto its side (vertical) to make room for building supported the top end, with pillows carefully placed as necessary. I could angle the kayak as much as I needed for the slanted pours. It was completed in several stages, because I had to do at least one pour for each side of each end. This kept the amount of epoxy from getting huge, but even the smaller amounts heated up a lot after a few minutes.

Best of all, I didn't have to worry about ambient temperature, wind, snow, animals disturbing the kayak from its vertical position, etc.

I still need to add one more small slanted end pour on the right side of the bow (the two sides are not even), but it's pretty much done. And I can do that any time.