rear sprocket hub or disc brake adapter?

[TipicoPate41]

Hello friends of motorized bicycles, I am new in this and just built my second bike. I have a little problem. My chain is always jumping off. It's because i mounted my sprocket (aftermarket part) directly where usually the disc brake is installed and it protrudes more than the motor pinion. (Picture 1 & 2)

So i see 2 options there:

Installing a adapter for the disc brake
-pro: It seems easy to mount
-contra: I can't adjust the adapter (maybe a bit to the outside adding washers between the disc brake attachment and the adapter) (Picture 3)

Installing a rear hub adapter
-pro: i could adjust it really good
-cons: i didn't found one with the right diameter yet (mine is about 32,5mm) so i may have to add a several layer between an 1,5" adapter and rear hub which is equally on every side. Also most of the sprockets included won't fit around the disc brake attachement, so i would have to cut off a bit in the middle. (Picture 4)

I also saw solutions with the disc brake attached to the sprocket, but to be honest i think i am not able to do the work. So i already installed a caliper brake instead of a disc brake.

I would be thankful for every answer and hint.

Many thanks in advance!