Hey guys, still here. I've been talking to manufacturers in my spare time. One supplier I talked to is talking to the major technical representatives and answering the big questions..
There may even be a stronger topology to the carbon tensile cords/nylonish clothish backing and tooth faces. I am testing fiberglass, polyester, kevlar (aramid), and HYBRID tensile corded emergency belts made in polyurethane (toughest?), EPDM (new school), nitrile, neoprene (old school), nylon (quiet) backing/teeth. polypropylene?
Belts are typically ordered in very wide sleeves and cut to width. This seems doable with a homemade jig (I may have linked the video of this already).
I plan on doing an emergency belt bulk order, at much cheaper prices than the first time around. I'm still testing samples now. I found a supplier that is able to do a bulk order in the scale we need of the most likely winner. If you are interested please reply and leave me a method to contact you (like your messages!) or PM me.
Sorry, I've only had time to work on this super late and removing a swingarm sucks. At least my belt breaking prematurely alerted me to the fact I have a bad swingarm bearing. I'll leave that to a real mechanic.
More info for you, fellow nerds:
https://assets.gates.com/content/dam/pdf-archive/GatesMectrol_Belt_Pulley_Catalog.pdf