I think I've seen most people use the MFI ultra low claw mount, but the B&T universal you have coming will probably work as well. The ultra low B&T really only works with the aimpoint mounts (ask me how I know). And then a standard aimpoint micro Scalarworks mount - probably absolute cowitness.
I'm looking to switch to this setup myself. Currently running the B&T low mount with a T1 but would like to get the dot up over the sight hood to declutter and allow me to shoot with nods.
The B&T Ultra Low mount wouldn't work with this: https://scalarworks.com/shop/quick-detach-mounts/leap-01/
It's a 1.9" Leap for Aimpoint. Wish they made one for the RMR that was 1.9". Would be pretty close to perfect I'd imagine