Crack the throttle and a back pack would suck you off. lol.
For a sport bike.... depending and if you could find the room, would go for a tank bag.
I toured and commuted on one of these. Honda had a clever latch system and neat integrated suit case handles. They sealed well. For trips, I added a tank bag and duffle on the rear. Circa '82
These are stock photos but years ago on my scoot, added a ATB turbo kit and a little extra

Ahhh, the 1980's...