Wizard of Draws wrote
I'm not sure how practical that would be. I rent, not own, and the plane
that I fly seems to keep a pretty full flight schedule of IFR students.

You might look for a faster/higher performance airplane to rent.
Those are usually not too busy. Something like a C-182 might fit the
bill.

How many people fly Angel Flights in a rental?

Not many, I admit - but it is doable. The key is finding a capable
and reliable rental - which, I admit, is rare and not cheap.

Some other ideas:

Get a glider rating. If possible, do it at a place that allows XC
flying in a rental (all of them will allow solo rental). There's not
much to getting a glider rating, but going on a cross-country flight
in one is another story. If you can find a place that trains off the
winch, so much the better. Where else can a civil pilot have the
experience of climbing 45 degrees nose up, 200 ft off the deck,
pulling back on the stick, and accelerating?

The tailwheel endorsement is a good idea, but make sure you do it at a
place that will rent you the airplane solo. It will take longer to
find and be more hassle, but the difference in what you learn is
dramatic.

The commercial is a waste and not much use, but how about some
aerobatic training? Again - make sure it's a place that will rent to
you for solo aerobatics.

Michael