Help with a particularly vexing key mapping

Hello -

I'm hoping a more experienced or capable BTT user can help me with this issue:

I recently bought a Drevo Bladmaster Pro keyboard to use wth my 2019 Macbook Pro running Mojave 10.14.6 (18G103). Out of the box the "Win" key on the left side of the keyboard maps to the OSX Command key. I would like to map the "Menu" key on the right side of the keyboard to emulate the Command key as well, but for the life of me I cannot find a way to do this. I've used BTT for years to map the right ALT key to act as a "forward delete" key but have been unable to do this. Any advice, recommendations, etc. would be greater appreciated.

Thank you.