I've seen one guitarist pull his belt such that the buckle is a few inches to the left of center. Or wear a nice shirt you either don't tuck in or so you don't have to wear a belt.
The other alternative that I exercise is to simply not care. Not being tongue-in-cheek; truly, just play it and not worry about marks. FWIW, I care for my instruments in terms of their health: humidity, not getting dropped, securely on wall or stand, etc. My gear
has to last so abuse is a huge no-no. But I don't sweat one drop over cosmetics. I used to, many decades ago. But since I've stopped that, I've felt far more liberated both in playing and owning nice instruments. FWIW, anyway
Edward