Glad you're not too hurt!
Try to eliminate the tensioner- sometimes a smaller sprocket will give you more clearance- as well as a btter cruise without opening the throttle. You may not be able to on a mountain bike frame though-
But this isn't by any means the first time I've heard this scenario involving the tensioner- so on my two cruiser builds- I've never used one
saves all kind of weight too- I used to have to wheel my bikes up a flight of stairs, so I built them light
also- I'd recommend a 415 chain- not sure what you mean by 41 chain- a 410?
anyway- the 415 is harder to work with as far as cutting it, but it gives more tolerance to any misallignment problems -
I use a 415 Industrial/Trike chain- which is the same width as standard 415 but with shorter verticle plates- much lighter and rolls much smoother- you can hear the difference too. Search it here or on the net- about $12 delivered
If you can- post a picture of your motor and sprocket allignment- taken from right behind the back sprocket- and we can see better if you can skip the tensioner.