I had a leak test done by a Camping World on a previous coach. They laid a sheet of plywood on the bed and sat this massive box on it. The top had a duct that sealed around the ceiling vent. When they started it up it sounded like a jet engine and I swear the walls bulged out. So no, I don't think a couple of Fantastic Fans will give you enough pressure for a meaningful test.
Bruce Dickson 2013 Thor Challenger 37GT, 5 Star Tune, Safe-T-Plus Steering Control with Air Trim, Roadmaster front and rear Sway Bars, SuperSteer rear Track Bar, Crossfires, 2012 Honda CRV on Blue Ox Aventa LX tow bar. Full timers since Jan 2012.