I can't answer your question but consider this:
I tried a monster retread to replace one tire. I had to open up the wheel fairing hole a little but the tire itself is a little larger.
Going forward, if you do go with the thicker tire, there really isn't going to be a significant difference as long as it fits under the top of the fairing. Once you open that hole for the larger tire, the tire opening is just larger and as long as you use that size tire the gap won't be any worse than standard. My Monster retread did fit under the fairing fine, and now that I've opened up the bottom a little, I'm just going to continue to buy monster retreads from now on.
Did they give you specs on how much larger a 10-ply tire is?