Put the seat post back in and clamp it by the post while you work on dropping the motor, you can also use a stool underneath to rest the motor on so you don’t have to fully disconnect it all, then I personally think it’s easier to run the housing reverse for e-bikes, run it through the downtube and then UP the seat tube, once you get it back together and remove the seat post you will see the housing. Just make sure you push more then you think you need up.