Sorry to here of the tire problems Rob. And befor I forget, I am new here as well, WELCOME to a really cool gathering of great folks from around the world. I ride big bikes too, so I can feel your troubles deep. When my brother and I did some conversions on our hogs, we had to invest into some extension hardware, which allowed for a belt drive unit on a 250mm wide wheel. It will be just the same for you on your ride, but not as drastict as a 250mm street tire.
I think if you shot us some pictures an some measurements in the tech section, some of us could help offer up a good fix it for your problems.
One thing I love the most in mechanicing is the chance to help engineer fixes for machines. 8-)