A slice of soft leather or neoprene will put an end to any marks off a bipod. Or you could go for a picatinny mounted or spigot mounted one providing there is enough of a forend to insert the spigot
I have sling studs on all my rifles and the slings only come off to go in the safe. Even on the range I find the sling a useful tool to tie you into the rifle, I hook it round my supporting elbow and use the tension as an extra guide to feel the consist of hold I have on the gun.
Atb. Hal