You sir, are amazing.
I rode down from KL to the Singapore border once, and it was hell. Riding down from bangkok must be a whole different ballgame.
Fwiw, I'm actually planning a bangkok trip with my girl and her friends sometime later this year, but it has to be in the family mini-suv to accommodate all her shopping!
Doesnt stop me from renting a bike in thailand though. I heard it's pretty easy& cheap to just rent a decent bike? My friend rented a 750 kawa on his last trip to koh samui for pennies.