Thanks guys!
I got the two screws off the left fender well and was able to pull the bumper cover just enough to pop out the dent. The top screw was a bit hard to get to, but I finally got it with a 10mm deep socket w/ flexible extension. The threads were rusted out and never completely tightened when reinserted. I might have to get a new screw from the dealer for piece of mind.
The thing that surprised me the most was the dozen or so smallish rocks that dropped out when the bumper was pulled back! They must have been wedged up there pretty good.
Now that the dent is out, the damage is less noticeable but there are still some gnarly scrapes. I'm not sure if these can be fixed other than replacing the entire bumper cover.
I'll post an updated picture tomorrow.
P.S. - It doesn't look like bumper covers are all that expensive:
https://www.amazon.com/Replacement-Toyota-Bumper-Partslink-TO1100243/dp/B004GCGOJY/
How much does it usually cost to have painted?