I think I have mixed feelings on the whole thing. First off, from a medical standpoint, I'm somewhat jaded because I run a clinic, and "disability" is a term that gets thrown around WAY too loosely. A person such as yourself with a bad knee, IMO, is not disabled. Your weight is no secret around this place, and that knee and foot infection would be a non-issue if the weight isn't where it is right now. I've struggled with weight my entire life, but April '08 I decided I had enough, and amd currently down 110 pounds, and it is absolutely amazing how many things DON'T hurt anymore. You are on a slippery slope with illness if that weight stays put brother, you won't have to worry about hunting at all in a few years if you are bed-ridden.
As for the legality of it, it is what it is. Yeah, its legal, great. But, you have worked your ass off to get a deer this year, so are you really going to be happy with one that you poked from the car window? Also, if you do shoot it, how do you plan to get it out of the woods and loaded into your vehicle? Right now may be the time to focus on your health and take a mulligan on this season.