and to answer you proportional question, I think for the kind of shoe you described the Nike Air Moire Mid (which proving impossible to find images of, ugh, it was an early 200's shoe and the first to have nike plus, designed by Mark Smith, I loved that shoe. Shot of the low top attached) would be a good reference, or even the Jordan T4G that I worked on, though that was a bit more hoops inspired. It was built on a running shoe last though.
Anyway, I did a little liquify on your sketch so you can see what I'm talking about. When I worked for D'Wayne Edwards in Jordan he wouldn't even look at a sketch at this level if it wasn't close enough to the right proportion, so he might have overly trained me to be a stickler here.
I know it is a lot less sexy, and you can cheat it a little more than I did, but I wanted to show the other extreme. The nike x Acronym Presto is another good reference (deconstructed stuff aside)