Only you know what you can endure, so play it slow and careful. If it looks too tough to get to, maybe you can direct someone to just move a few things carefully to get the full heat you want. Its not good to force either yourself or the blend door mechanism.
Just go slowly and carefully.

 

Well, tried the access through the glovebox....did not work for me.

I am throwing in the towel.......have ordered "2" 12V hair dryers and that will have to get me through the winter. I know it will be cold but fortunately I don't have to drive the truck everyday. I have 2 other winter vehicles with heat. Good thing our New England winters are only 5 months long.