What would a 7mm do to the hide of a wolf within 75 yards? Would it ruin the hide for a mount/rug? Someone once told me that with that much velocity at close range, the hole wouldn't be as big as if it were out a couple hundred yards.

Depends on what bullet you used. The more heavily constructed the bullet isthe less pelt damage you should get. If you could find some FMJ that would be best for wolves if you want as little damage to the pelt as possible.

Someone lied to you.

Don't use a Nosler ballistic tip if you want small holes in the pelt. I shot a smallish doe once, not much difference in size to a wolf, and the entrance hole was the size of my finger, the exit was the size of my fist. Worked great fora deer but too much damage for the pelt.

Who cares.. Shoot them anyway!