We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember Appelation Controlee
saying something like:

The door is a large one compared to
what's typical today, and it's heavy, so I want to take a millimetre or two
off the area that's causing the problem, but I want to do it without
removing the door.

Other than the obvious angle grinder, is there an easy way to do this?

With the non-removal of the door in mind, I'd think about running a
hacksaw blade along the bottom, in a padsaw handle. Can't you take the
triangular drip section off, to work on it?