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As you see in the picture the peddles attach directly to the front wheel,(like a unicicyle).
I am looking at adding a crank motor and chain to the front wheel but I am lost as to how to do that and not have the peddles spin when the motor is running. The hub is a standard coaster freewheel. Open to ideas thinking flip flop hub left side has a spacer and the right has an attached sprocket, axel is 118mm.

Why not use a front hub motor.

I use a front 500W hub motor on my trailer
with a 36V Lit-Ion battery mounted to the deck
works very well.

Motorize the trailer so you can move it to another bike when you get tired of going 3 mph on that trike.

Hub is out none have rotating stator and I do not have a machine shop to modify one

I go a lot faster but want a motor to extend my excursions. Can not use a pusher steering is in the back

Steering is in the back? You don't want to go any faster, you will die. There is a reason no vehicles are steered by the back except slow moving vehicles like fork lifts.