Bike Friday has a Prototype 20" wheel design
where they relocated the rear fold pivot ahead of the BB.

so they can use the Gates Toothed belt drive..

that is already an option on the Tikit Folder.

As you see from Vic's picture the hinge is behind the BB, on the travel bikes.
so some sort of tensioner is needed..

I have a 2 pulley spring-loaded tensioner on mine..