The far end of the wires will be terminated in sealed auto connectors, the same as already used on the bikes. I have been producing similar items (without displays) for nearly 10 years without a single failure so I am confident that side of the project will seal fine. The epoxy I use is only 5 minute stuff as I found the 24 hour stuff wicked like water just as you said. Any wicking at the box end actually aids in the sealing. Having said that I have also considered a socket on the box but I don't think i can find a sealed one small enough. The box is only going to be 50mm x 40mm and about 20mm high.