Welcome to the wide world of skoolies!
Before we suggest a particular drivetrain or configuration, I think its important to know a bit more about how you'd like to travel. It sounds like you're pretty flexible - you need room for one person, and you don't have a lot of stuff. That means that you could fit into just about any type of bus - a cutaway van, a shortie on a full-size chassis, or a full-size 40' bus.
For example, are you planning on towing a car behind your bus? Having a car (or jeep - check out some of the places Dory the bus has gone) means you can park the bus, and explore a bit more in something that fits in a parking space. You have to plan ahead to go food shopping in a 40' bus. A bus on a cutaway van chassis won't tow a car as well - but the whole bus will fit in the supermarket parking lot.
A lot of people split the difference with a bike or scooter. (You can carry it on a hitch behind the bus, or some people design the rear part of their bus to be more of an unfinished garage/storage area.)
Also, how much room do you want to have - a bus is basically a rectangle, 8 feet wide. The largest buses will give you 35-38 feet of living space (easily giving you a dedicated bedroom, bathroom, and living room/kitchen), while a cutaway van is about 12 feet long - so you end up with everything in 1 "room."
It's a lot of think about - and there's tons of discussions about all that stuff here, so you've come to the right place.