If the knot goes all the way through the put some tyvek tape under the bottom. The tyvek tape is available at big box stores. It is used to seal up tyvek house sealing sheathing. The thing about the tyvek is epoxy does not stick to it.
If you are worried about temperature check with the OEM. For the MAS they suggest if it is cold you put the part A in a sink with hot water and let it warm up. So check if that works with your epoxy. Then after getting it poured take it into the house where it is temperature controlled. I would not pour the epoxy in the house because the potential for disaster is too great. If you get a leak it is very hard to stop and inside the house you will make a mess and be persona non gratis with the significant other. Also you might want to make a small dam around the knot with the tyvek tape so while carrying the project the epoxy does not run out around the project.
