I'm thinking that the scope offset issue is more of a theoretical issue than a practical issue. M1C sniper rifles had a scope mount that was even more offset than that found on a K-31 clamp-on mount.
I haven't tested a clamp on mount further than 100 yards yet, but I'm assuming that with the scope offset by about an inch, if zero'd at 100 yards, it shouldn't be off by more than an inch at 200 yards and maybe double that at 300 yards. Crosswinds are going to have much more effect on windage than scope offset.