OK! Last post from me unless questioned.
See my previous post. I got the cheap slab of quartz countertop. It's 1250mm long and 150mm wide. I reckon this is the absolute perfect size. I will explain why shortly...
It fit perfectly between my widest bench dog setting, which was nice. I decided to just use non-adhesive paper (80 grit) and contact adhesive. It was the same price for 5m of this stuff and an aerosol bottle of adhesive as 4m of adhesive-backed from ebay, and it was right down the road at The Big Green Shed (D.W. - that's a nickname for the Aussie version of Lowes/Home Depot).
I retracted the blade and set to work. The width of the slab is almost perfect for the 115mm wide sandpaper. Given the length, I was able to take full length strokes with the #7, hence my comment about the perfect length.
All in all it took about five minutes to lap the 7 with the corrugated sole (technically a 7C). I then sharpened up and was immediately able to get full width, super fine shavings. The initial problem was that I had to advance the blade unreasonably far to get a shaving at all, and when I finally did, it tended to be far more coarse than desired. Completely fixed.
Here's a shot of it. Sorry, the bright white of the quartz tricked the phone into thinking I was photographing the sun or something...
Attachment 353993
Cheers to everyone for the ideas and help along the way. This method comes highly recommended and cost me $20 plus $20 in consumables which I can use to lap at least four more planes.
Luke