I'll have to take a peek under mine in the morning to see space wise what you are working with..but in terms of a snorkel exhaust pipe that is pointed upwards, I feel that it'd be easier to put together an exhaust with a stack coming out of inside the bed, like this maybe?
Or did you want the stack coming out the side of the bed more?
Sry for the slow reply guys ... The hummer style is what I'm after but I wanted it coming out of the bed side like that .. I can't do a bed mounted exhaust cause I'm getting a soft topper by a company called softopper.. The kind that fold up