For those who do not want anything to do with a Picatinny fastener, Trijicon also offers their RM57 and RM58 bases. These are designed for ribs and would require making a custom insert to go in the dovetail with proper slots to accept the Trijicon attachment.

RM57 for 11-12 mm ribs.

RM58 for 14-16 mm ribs.

I don't think it is difficult to craft a double rifle mount for a Trijicon RMR, given the available attachments from Trijicon.

Curl