it'll be tricky. I was unable to get 129 from York from the edge of my big dish (and I can get close to 100 with 82 from the opposite side), but I can't get any signal for 129.
With a superdish 105, the 129 lnb will be in a far from optimal position to pull in 129. And being at the edge of the footprint will worsen that. I'd use a dedicated 18" dish (or better yet, 24") to try and pull it in.