squeeze in some dielectric grease or silicone.
they don't get any elements that should be harmful to them anyway. main thing is to keep oxygen off of the copper wires to keep corrosion away so silicone or dielectric grease will do just that. put some in before inserting the wire and after on the connectors exposed end if you want more protection.
crimp on style should be fine and no need to solder them. i like to double up the exposed wire end so the crimp gets twice the wires and makes a better bond and fit. try to push the jacket tight to the crimp stop so none of the copper is exposed on the back side of the crimp.
soldering can cause corrosion with the flux and or acid core solder.