I think I am going to stick with the bilge pump switch that doesn't have any moving parts.
I found some submersible lights which are kinda pricey but they are rated as ip68 (the IP68 rating must always be better than the IP67 rating, that means that the instrument may be submersed for at least one meter ~3')
I might just order one set of red, one of blue and one white and see what they look like in the water on the trailer.
I am pretty sure that I will use white on the pontoon trailer, but the boat trailer is red and I may go with either the red or the blue?????