I use Saunders easels, and have no problem with paper alignment.
The easel has a shallow groove into which the top of the paper slides, holding it square.
I also have a Saunders(???) borderless easel. It has a fixed rail on top and movable rails on each side.
The side rails are angled very slightly inward as you move up, away from the paper.
This angle tries to hold the paper flat, and does a reasonable job, even with fiber.
The main problem with these is that the side rails are natural aluminum, and thus reflective,
so some light from outside the printing area gets bounced back onto the print.
I suppose I could paint them black, but I've not yet done so.
If you use an overmat, nobody can tell whether the original print is bordered or not.