Large gap around new toilet due to improper floor installation
I ended up getting this fixed in what I suspect is the only way it would get fixed - I had the floor fixed.  I was planning on doing it myself but when the toilet started leaking a bit (presumably because of some residual rocking due to the uneven floor) I finally just hired someone to come out and fix it quickly and correctly.

The toilet was conveniently located in a small alcove, maybe 4'x4' (wall on one side and the back, open in front, and a 3 foot wall on right).  This made it easy to pull up the toilet, pull up a minimum of floor (about 8 "planks" total), and properly cut the floor so that it fits snugly around the toilet flange.  The toilet was then reinstalled normally, and it looks perfect.  If I had more time it would have been a very easy DIY project.  Fixing the floor probably didn't take more than an hour total.