IN and OUT are the two highest amperage loaded points in the circuit. I go to the hardware store and purchase appropriate size tubular wire brushes to fit the holes. Disconnect from shore power and inverter, remove one wire at a time and ream the hole with the wire brush until it gleams. Scrape the wire strands bright shiny clean with a utility knife. Brush on the colloidal copper and tighten the set screw. You need not do this to the two holes with the long screws that attach the buss to the fixture.
Next, do the POSITIVE feed wire in and out connections. You'll have to "Do Them All" In and out wires. Then go do the buss and feeds in your fuse and breaker panel. Do this once and do it right. But you do need to re-check to make sure something weird is not causing the set screws to loosen. I "trust" nothing.
TIN plating is only moderately effective in stopping corrosion and electrolysis. Copper can be used in a DIRECT aluminum to copper termination or junction. Gold, is invincible except with aqua rigea (don't give me a hard time with this SPELL CHECKER!) but we know how that goes, sigh.
All Hardware stores of note sell colloidal copper "assembly" compounds in various sizes from blit tubes to tubs.
It's nice to do something once, do it correctly, then do plop in a lounger by the pool crack open a brewskie and say "ahhhh"