Well, let me make you feel better. I've got stubby fingers. Blues shuffles in G (3rd fret) were always hard, in F near impossible. They still are. If you gave me a choice, I'm choosing A or E baby! I'm just one guy, but hope that makes you feel better.
I will say though that they definitely get better and easier the more I play them, and if I was doing lots of blues in G over a few weeks or months, I'd probably even get to stretch to the b7. But it's been a while and I find that I lose stretchiness if I keep going for A all the time, or Bb, or some other cop-out key. I can't stretch to the b7 (ie 3rd to 8th fret) in G at the moment, I just tried.
(edit: emoticon chosen to show facial expression while trying lol)