I'm back after a few years of being gone. I originally had a 21 ft. Nomad/Skyline Trailrider toyhauler. Interests changed and life got busy and it sat in storage for a few years and eventually sold it...
take an "OLD" tooth brush.. open valve and clean around disk and seal/seat area... paper or "OTHER" stuff could be preventing it from closing completely ...
Nice Trailer.. Have Fun. I take my street motorcycle with me the same way you take your bike.
as for bounce .. I think Monroe Shocks makes several kits to fit trailers.