That's what my last roommate did. She practiced for a couple weeks on an old CB350 I had, passed the test, and bought a nice Zuk GS500E. Perfect for her 40 mile/day commute.
I've never been a fan of 2up riding. Takes me off my game. I've thrown a few down the road. Can't be 100% all the time. I don't want to know how it feels to have hurt someone because I
mucked up.