May not be what you're asking about, but this is what I do for highway or night trailering. LED's on the trailer stay on the trailer, and passes inspection every year that way. LED's (non-submersible) on the engine are just wedged on with bunk carpet inside the legs, and a bungie to hold it there just in case. Takes seconds to unplug and stow in the tow beast. If I drill a hole in it, I could cable it to the OB to slow someone down who's trying to steal it, but I don't leave it unattended like that anyway, so I haven't bothered (yet).
The mast ends just about even with the lights, so no extra marking light is required on that. Stop/turn/tail lights are right in everyone's face, too, so less chance of getting run into in stop and go traffic. Getting too close, even in a car, buries the trailer lights out of sight, but these are pretty hard to miss.