It kind of depends on the scooter. If it's Chinese, you should have a support van with a couple of spare scooters worth of parts.
Re. the fuel bottle, that's a good idea, but get one that was designed to carry fuel; don't be tempted to put it in a water bottle.
Rather than the can of fix-a-flat, I'd bring tools to plug your tubeless tire. Or maybe both.
Hopefully, you're not planning on camping, because that gear alone is going to fill up your scooter. Better off to map out EconoLodges on the route, or cheap ma 'n pa motels.
Other items:
- Rain suit
- An old wash cloth soaked in Windex in a ziploc bag to wipe bugs off your visor
- A multi-tool and its bit kit (ex. Leatherman Surge or Gerber MP600 Pro Scout)
- A Beadrider beaded seat cover
- Your old socks and underwear; throw them out along the way
- Roadside assistance plan (check that your company will tow bikes; State Farm doesn't, which I found out when stranded, one time)
What's the longest trip you've taken to date? If it's just a hundred miles or two, you might want to do a dry one in which you travel the whole weekend. Things you should have brought will present themselves.
Good luck; let us know how it goes!