If your base packed weight is under 20 pounds, I agree you can pretty much take any bike you want and pack it however you want, even carry it on your back. If you stay on pavement, wheels and tires can be anything, too. Same with gear ratios--it just doesn't matter much with greatly reduced loads.

My definition of light touring encompasses self-contained touring and mostly camping, just with a lot less and lighter stuff than traditional five-pack tourers. The mindset includes packing for a cycling trip, not a camping trip, and spending a lot more time on the bike and touring than camping.

I weigh 150 and my base load (no food or water) is under 15 pounds in two panniers, no handlebar bag. My last long XC tour (4500 miles on pavement) was on 32 spoke wheels and 25 mm tires which were a little too heavy for the ride, I thought. Next big ride the bike and tires will be lighter.

Enjoy your ride. Overnighters like that are a great way to shake down for longer rides.