Allow re-map of mouse right click without modifier

Description of bug/feature request/question:

Want to remap right-click on my mouse to another button, but BTT wants me to select a modifier.

I would like to re-map that button without a modifier. (In this case I want to switch the middle button and the right click button and not have to use a modifier for the old right click button)

There is an issue for this on github but I can't find it here:

Affected input device (e.g. MacBook Trackpad, Magic Mouse/Trackpad, Touch Bar, etc.):

Evoluent external USB VerticalMouse 4 (bluetooth)

Device information:

Type of Mac: MBP
macOS version: High Sierra
BetterTouchTool version: 2.667 latest