Burner orientation on Pressure Pro skid

[Heath71]

Enclosed trailer ventilation

I’m going to pick up a 7x14 enclosed trailer on Wednesday. I’m putting a 8gpm hot water skid towards the rear. The way the skid is built, I will have to add some length to the muffler. I plan on going to a muffler shop and letting the pros take care of that. Should I vent it straight out the back in the same direction the burner will be blowing? Or duct it to the floor? My first choice to to just have them make a 90 with about 1 1/2 ft length pointing towards the back. Currently the exhaust will…