I generally prefer to solder connections and insulate with shrink tube.
If you want to use crimp type connectors, I believe there are some with a gel inside that reduces chances of corrosion, especially if used in exposed areas such as feed wires for electric brakes. Never tried them but that is what I would look for.
In trouble-shooting things that were not working on trailers, I have often found the problem to be old crimp connectors and wire nuts that were full of corrosion and as a result were open circuit - the connections pretty much just fell apart when touched.
Brian & Connie Mitchell
2005 Classic 30'
Hensley Arrow / Centramatics
2008 GMC Sierra SLT 2500HD,4x4,Crew Cab, Diesel, Leer cap.