Is it a bad idea to rely on a magic gear on an ebike?

Basically I want to convert my 6 speed ebike to single speed because I find the gears redundant with a motor.
The problem is the frame has vertical dropouts but if I'm simplifying things I'd rather not use a chain tensioner.

Would this be a decent idea? Has anyone ever done it? Or should I just suck it up and get an ugly tensioner?