A rear-steering machine can start to oscillate very easily. They had a few rear steering cars but they were death traps.

They've had various forms of treadle drive; you could probably google up some results on how well they worked or find the info in an old book.

I see you have found the problem of how to keep the pedals from striking the front wheel while steering a short wheelbase recumbent without using a small front wheel or a high seating position. Other builders just use front wheel drive with front wheel steering, or a long wheelbase, or a small front wheel which steers, in order to clear the pedals. Rear steering just doesn't work unless you're going slow.

Anyway, I don't want to be a naysayer but just so you're aware, that's the crux of the problem: when you steer with the rear, it can start to oscillate and get away from you. Your bike would have to solve that problem if it were to work.