Sitting straight up is generally not such a hot idea for longer rides as it puts more weight on your butt and makes it more difficult pedal effectively.
And increases air drag.
Seems like the Bad boy is listed as having an 1 1/8" steerer, which would make swapping in another stem with the bar clamp diameter of your choice easy.
Although I wouldn't hesitate to use shims.
Should be something on this list that'll work:
https://www.amazon.com/s/ref=nb_sb_n...ebar+shim+31.8