Obviously, there is no ways to print 35mm negative to fill the entire space available on 8x10 paper. 35mm frame is 2:3 aspect ratio. (24mm by 36mm I think?) So that only thing you can do is to either use 4 blade easel or make a mask out of cardboard (this is what I do) and settle on wasting some space on paper or not print entire frame on the negative.

Since I do not have a 4 blade easel, I made several cardboard windows that covers 8x10 paper but have a smaller window opening. I tape this to back of my "quick easel" and print. Cheap and works well.

What are you going to do with your prints? Keep it in folder? Frame them? Keep them in box? That usually dictates what size you'd want to print and even printing full frame is feasible. Most of the time, I end up cropping mine.