There are a cracking routes in Simon's book that will help you out. But if I had to ride it this will be the the route.
Thetford to Mundford, to Swaffham, to Kings Lynn, to Colsterworth via Spalding and Bourne (boring bit), Colsterworth to Ancaster or keep going straight on the A52 and turn right to Sleaford (don't mind the average speed cameras on the A52, cameras are facing the wrong way), Sleaford to Horncastle, to Louth (past Cadwell Park), Louth to Market Rasen, Market Rasen to Humber Bridge and on to Beverly, to Wetwang, to Malton (you might go past Castle Howard, an experience just to ride the old road through the gates), to Helmsley. You can stay in Helmsley at The Feathers. Parking round the back. Food is very good to excellent. The Black Swan is undergoing restoration unfortunately.
Helmsley (via Sutton Bank) to Thirsk, to Rippon. From here you can go southerly or northerly route.
Southerly. Rippon to Pateley Bridge, to Grassington, to Kettlewell to Ayesgarth (Ayesgarth Falls), to Hawes, to Thwaite, to Brough.
Northerly. Rippon to Masham, to Leyburn, to Reeth, to Whaw, to Kaber, to Brough.
Brough take the A66 to Penrith. Penrith to Alston
(stop at the top which was the Hartside Cafe), Alston to Lambley, to Brampton, to Longtown, to Gretna Green. Follow the A75 all the way to Stanraer or turn off at Castle Douglas (Red Kite feeding station at Laurieston) to New Galloway, to Newton Steward and back on the A75.
Accommodation is always a discussion on these pages. I have not really bothered with bike friendly hotels or parking. Once you are in the countryside few people will actually bother a motorcycle. The Buck in Reeth has got none. Had a very good sleep there. The bike stayed right outside the door of The Buccleuch & Queensberry Arms in Thornhill on a busy road and nobody tried to nick the instruments. All you need for such a heavy bike and being a short arse is just hard standing. You will be fine. If you look through the route above just pick a spot that looks ok. Hawes is popular with bikers and it has a community garage just up the road from The Crown. But book ahead, the place is popular. Enjoy.