I would think you're correct about anything greater than 5x to be too long. You may run into some eye relief issues, unless you're running a monolithic upper and the RDS way up onto the handguard, but that's another topic of discussion. I always thought this bit of kit to be interesting, not sure if this will suit your purpose:
http://www.mylucidgear.com/magnifiers.php
Good luck.
"We are oft to blame in this / 'Tis too much proved -- that with devotion's visage / And pious action we do sugar o'er / The devil himself."
Μολὼν λαβέ | NRA Lifetime Member
Bookmarks