My temp fix on my 96? Explorer I had was I cut into the plenum either behind the glove compartment or under it. Can't recall. Big enough to get my hand in there. Then I figured out what way the door should go and used some epoxy playdoh type stuff, can't quite remember the name. I has the consistency of play doh and I was able to glue the door in one position. Course you are commited after that. Then I used some aluminum tape, 2" stuff, to cover the hole.
Maybe you could drill a hole in the door with a dremel then some holes in the plenum and zip it in. So if winter comes and you haven't fixed it then you could move it around. I like your zip tie idea. I'd vac the shavings out also so they don't get in your air system.
Make sure it's not just the motor that's bad before cutting in.