So what are you curing for? I've cured boneless pork loins for Canadian bacon without removing anything, but the commercially available loins around here have almost no fat. I always buy the rib end to cure.
I've also cured loins for Black Forest Ham, a recipe that was entrusted to me by a forum member with conditions, that I have trimmed the extra fat from. I've had no problems with the cure penetrating either way...