We use smoke machines to find vacuum leaks on engines. Using it for wind noises and water leaks is somewhat dicey. The one I use takes mineral (baby) oil and the smoke is similar to that from old Lionel train engines. It does NOT work too good to fill a large area with smoke to try to find the leaks. You can test locally with a helper inside, aiming the hose at the suspect areas. It works better to be inside out of the wind (yeah right!) and lightly pressurize the trailer with a fan, and blow the smoke against the outside suspect areas to try to find where there is a draft blowing out. The soap bubble method looks better for this type of leak. A smoke machine would ROCK for finding water system leaks, if you blew all the water out first. For the record, my low-end smoke machine cost $999 a few years ago; you need to need it a lot to own one.
Now, talking about "vacuum methods," what about this: applying a slight VACUUM to the inside of the trailer, to help pull sealer INTO the seams as you go? It seems that this would do a better job, but especially on larger leaks, you'd have to be careful not to end up with stalactites of sealer all down something nice inside.
For that matter, in an emergency downpour/new gusher situation, maybe applying a slight overpressure would slow down or stop the leak for the duration, and you wouldn't have to get rained on even!
It seems I love the mountains and deserts more than my friends do. I sure miss them!
1971 Streamline Imperial project "Silver Snausage", 1985 Coleman tent trailer, 1964 Little Dipper, 1975 Northwest "Proto Toyhauler", 2004 Harbor Freight folding, still seeking my Airstream.