Gary,
I was thinking of dropping some weight, namely the SBS bar, and mounting the TAK on top of the Vixen with a rail and ring set for the tak. Seems to be a hassle mounting a single tak clamshell on a vixen dovetail system and I wasn't planning on buying a 2nd clamshell. There are mounting points on the vixen for a rail and an ADM rail and ring kit should work. I guess I should measure it and ring around