Hey man I'm so sorry to hear of the upset. I followed your builds closely.
My sis was recently hit hard on her Vespa and needed major reparations both medical and mechanical. Like Old75 said, these insurance guys love paper trails. My sister sought a lawyer and gave us great "tips" for getting maximum monetary returns: photograph everything, especially one-off parts; take photos to a reputable mechanic and ask him to appraise your bike with mods; find out their insurance limits, and your limits (especially comprehensive and uninsured/under-insured limits); create a diary of how upset and depressed you are and ask your sis to do the same (write in it often and it can be a gold mine!); in the event your bike is totaled, fight to get a fair value for it, then buy it back before it goes to auction, however, it may need a salvage or worse, a parts-only title. If after you've maxed out the insurance payouts and you still fell wronged, write the guy and tell him you'll sue him personally until your victimization is completely paid for. If he ignores you, find a lawyer and pursue arbitration or settlement. That's all I can think of now.
So sorry you have to look at a flattened bike...Good Luck