Thank you everyone for all your stories and advice. Yes, my little buddy is a great dog, and such a trooper!
Simon weighs about 55 pounds, and I can pick him up and carry him moderate distances (I've done that a few times over the last week when he seems like he's having trouble with stairs). I am a little concerned about the recovery, but my roommate's dog (who has since passed away) had very poor mobility, and we had ramps for her off the deck into the "elimination area", so luckily those are still around and can be pressed into service for Simon.
I'm going to call a few other places tomorrow for estimates on the non-TPLO, since so many of you have had (or know of) good results with it, and then get the procedure scheduled as soon as possible. I don't want to leave it too long, but I have to be back east for a week in 2 weeks, so I may have to schedule it for after that if I can't line up some good puppycare for him when I'm gone. Luckily, Simon has a huge fan club!
And because I can't resist, if you thought that other photo of him was kissable, how about this one? (For those of you who can't read pitbull lips, he's saying "wooo wooo")
Keep calm and carry on...