Trying to seal everything that could leak in an older TT

Never use any silicone sealants on the exterior of the RV. If you thought repairing a storage/floor area was difficult, removing old failed silicone from all over an RV exterior will be about the same amount of aggravation. Asphaltic roof sealants will compare to silicone, don't use them.

Most experienced RV users have found that Dicor or Geocel Proflex, both polymer based sealants are the ones to use. They are formulated for the movement of the trailer and will not degrade as quickly in weather.