Interesting thought, but I don't think it would ever happen. Here's why...
The schools were split up because even in 6 man there's large 6 man schools and smaller ones and the larger ones were always winning state for obvious reasons. Larger school=larger talent pool.
If I were the coach of a larger school that won state I'd never want to play the small school that won state.
What's there to win? If you do win, but deal, you should have, that's why there's D1 and D2 to begin with. The only potential reward is for the smaller school if they should win. If they lose, big deal, they should have.
The better solution in my opinion would be a state champ vs state champ (of a different state).