I'm not sure I follow what your asking.
I wouldn't put the pressures of a sling on the air tube. It's just asking for trouble. But, I think shooting from a bipod that is partially supported by the stock and the air tube is ok.
If you've got the synthetic stock, I'd use T-nuts to distribute the pressure over a larger surface area.
Ahhh, I know what you mean....
I think you'd end up with a very tall mounting setup. The more pieces you add, the more potential for play in the system. If you're looking for a sling as well as a bipod, I think the Atlas mount has a spot for a quick detach piece that is common on slings. Essentially, you could have a solid base, very good bipod, and QD sling connection point all in one. If you used the T-nuts, it would also be very secure.
Tom