My plans are to add to what auto manufacturers use in their products, rubber drain tubes. These allow drainage & breathing yet prevents water from splashing up into the holes.
What I have discovered after obtaining & rebuilding my '76 Sovereign
is that AIRSTREAM fail to seal the 'underbite' lap where the bellypan wraps over (instead of under) the sidewall skins. Big mistake!! Even though it was/is the production method.
Since this joint was not sealed it was a HUGE water inlet with no place to go except linger it the perimeters of our trailers. Being soaked up by what little insulation was there and into the wood floor like a sponge and causing a slow death -by corrosion- to the frame members, mostly the outriggers and of course wood floor. Was this "Planned Obsolencence?" ARRGGH!! Shame on AIRSTREAM!
Think about this, water in with no way out? Hmm, would we build a house this way?
Anyway, I have replace several outriggers, oddly most were on the roadside, replaced the entire floor with R13 fiberglass & new perimeter belly wraps and will be sealing this critical area at the belt line (with VULKEM) & installing automotive type body drain tubes throughout as well.