.
Derailleur Hangers Demystified - Red Clover Components

...scroll down a little to get to Simplex solutions. But fiddling around with modifying one of your existing long cage examples might work.

It's not that difficult to notch a tab in the dropout and just go with Suntour front and rear, which is probably the most durable approach. Just look at the pictures, and maybe look at a standard rear drive side dropout, go very slowly and carefully, if you decide to go that route.