First Gen bonesteel w/ the picatinny but no mlok? I can see how that could happen if you charged from underneath.
If you're a RH shooter -- my advice would be to try turning your gun 45* so that CH is vertical (similar to position when using offset irons w/ an AR15) and use your support hand over the top.
Alternatively, go with Bonesteel Gen 2 with reduced and scalloped picatinny, and sell your Gen 1. OR be prepared to offer and pay a small fortune for an NEA lower hg.
You could probably fab something with pipe, pipe cap, and tapped for setscrews, but if you're friendly w/ any local machinists they might just make something for you -- just know that stopping the spin will be difficult short of divoting your CH at set screw locations.
But do be aware that the more weight you add to your bolt carrier, the more likely you are to cause malfunctions or even damage your receiver or bcg with excessive recoil due to extra weight...
*No, not aware of anything commercially. Possible that one of the clamp on AK or galil options might fit but haven't tried.