Just prior to swapping out the Yuminashi vario with the Daytona vario(which was when the problems popped up), I had some massive takeoff lag. Doing some online searching, I figured it was the clutch bell being glazed. The suggestion on the Goldwing forums was to engage the front brake and open the throttle to about 3000-4000rpms for a few seconds. I did that a LOT, and it was about 10 seconds each time.
I figure that's actually the most likely candidate for eating the belt.
Not too sure how to feel about mods. For sure you should be able to do them all yourself, or else just don't do it. Because a scooter shop and a motorcycle dealer(both highly rated on Yelp) both took a look at the transmission, but evidently only I was bothered by the thick layer of black crap all over the inside. Granted, neither of them broke the fairings, but I resolved the issue with 2 hours of work...hopefully.
I'll test it on the highway tomorrow

I'm still certain I have neither the space, the time, nor the expertise to shove a larger throttle body and throttle cable in there, so I'd still go ahead with selling the thing and running my sweet new CB300F full stock.