Don,
Making the change isn't over my head from the perspective of my ability to do the work. I'm more concerned about a flawless execution of a deeply flawed strategy.

And I appreciate your advice about the Rick experience on this board, but I have yet to see any experience relating directly to this. I've gotten suggestions and warnings (which I appreciate), but no concrete data (i.e. "I tried it. It doesn't work").
I gave this a much more in-depth look. The covers are the same height, as are the pickups. When you put the toaster cover on the humbucker, the flange doesn't sit flush with the base. The black plastic on the humbucker looks to be a cap on top of the coils. I tend to think that the crown on top of the cap is there only to fit flush with the cover; it's purely cosmetic. Of course, I also tend to think that I could be wrong, and there's the rub.
I would guess that it's a very simple operation to remove a 3/8" wide channel going right down the center of the cap to provide clearance for the center bar in the toaster cover. The only question is the material being removed. If it's just plastic/resin/whatever, the risk is minimal. I mean, would the cap be so thin that the coils are within 1/32" of the top of the pickup?
If I could remove the plastic cap, I'd know for sure. However, I don't know how the cap is attached to the pickup. I'm leery of using heat to break any glue bond, and trying to gently pry it off doesn't sound like a great idea, as you're prying against the circuit board (and not a metal frame).
If I didn't just pay $70 for this pickup, if I didn't plan to put it in a guitar in about 2 weeks, and if the upside was greater than a strictly cosmetic "benefit" of dubious value, I'd probably go for it. If the pickup ends up in the parts box, I may have to satisfy my curiosity. If I do, I'll let you all know.