I am still looking for the right option on that too, I just picked up a scope mount that attaches like a side saddle, it is in the mail. I am hoping I will be able to modify it to work.
Most of the lights I have picked up are not the 1" lights that you can find any mount for. They are closer to 30mm in diameter, which makes it harder to find a mount.
I am interested if anyone else has found something to work with the vent rib as well.