My leak test setup

Thanks guys. I put weather stripping around the top of the tub. The item on top of the 2x6 is a lead anchor to keep it pressed down nice and tight. My only worry was that the anchor would fall off and fall through my roof, lol. I'm glad to report that wasn't the case and it was nice and solid. I just showed this to a coworker and he said he needs to do the same thing to his trailer but is going to try it with his electric leaf blower. I would imagine it puts out enough air to suffice.

Oh and the flange on the tub is a 3" toilet ring gasket. I sandwiched weather stripping between it and the tub as well. PVC is also 3" with a 3" hole cut in the tub with a hole saw.