Very good question. My husband is disabled and should not lift and carry much and I have degenerative arthritis in my lower back and bursitis in my left hip which makes carrying things extremelly painful. We found a flat cart with wheels that works wonderful for transporting groceries and such from the car and moving items around the house. It has really helped us a lot; but we do not have any stairs where we live. Just thought of this, those high carts like they use in hospitals and such (not the huge ones, but the smaller ones) would they work for you to wheel it to the back of your car and be able to slide your machine onto the top of it, without lifting. For the life of me, I can not remember the proper name, but we used to have one. It had three layers and was lightweight and so easy to wheel around.
I do hope that you can find a solution that works for you.