FB paper has a definite curl.
I was thinking of this too. I have the Saunders standard easel and a few other ones. I used to use fixed size easels since they are easy. But some of the standard sizes are too small for my standard photo frames. So I had to get more print from the borders. I tried a couple of things and all work fine.
I have an old easel that there is a knob used to adjust size of the borders. So I adjusted the borders to be very thin, 1/4 or smaller if you like. I also used a 4 bladed easel (like the Saudners) and set the borders to be thin too.
I regularly use a Saunders 11x14 four bladed easel and print with a 1/4 inch border.
For small prints (4x5 or 4x6) I have a Beseler borderless easel. This one has two "bars" that are adjustable and I make these to be about 1/16th inch or 1mm smaller than the long dimension of the paper. this holds the paper flat and gives a borderless print.
Get the paper flat is the biggest priority. For wide paper cut from roll, you'll have to put on the blade to flatten it. 2-blade probably won't do it.
I tried using some double-sided scotch tape tonight to hold the paper flat on the easel and that worked out well. Six small pieces were enough to hold it down and no problems getting the paper unstuck.
Do you run the risk of damaging the paper?
I've resorted to the same kind of double-sided tape since I started this thread. It works well, but the trick is not to apply too much pressure when placing the paper on the easel; otherwise the tape will come up with the paper.