How to fit a diode in the 4b/camper?

I have installed an LED reversing light in my camper, which has a line to the car reverse light, and a switch in the camper to turn it on so it also lights up camp site. But being the electrical giant I am, LOL, I managed to arrange it so that when the trailer is connected (like for overnights stops), the switch also turns on the car reverse lights, which I don’t want.

I bought a stopping diode from Jaycar, to prevent flow of electricity from camper batteries to car reverse light – large 6amp one just because it was more robust.

But how do I fit it – just looks a bit vulnerable. I assume I solder it in, but do you shrink wrap the whole thing or just the metal pins/wire? Should it just sit in split tube or does it need better protection than that – if so, what?

Thanks for any replies.