Thanks to everyone that contributed to this thread. I will be using the magnetic trailer lights when I go to pick it up. I always had that in the back of my mind as the likely solution, but I figured that eventually I would be modifying the trailer wiring so I could tow it with a civilian truck anyway so might as well trace down the details now.
I think that the bulbs all have the same diameter bayonet style plug, the difference being the height of the bulb. The two civilian equivalent bulbs appear to be the Sylvania 1156, and Sylvania 97. I found this cross reference site that shows them to be the same size.
cross reference link
I suspect that the difference in height is to support a larger / brighter 1156 bulb. I will probably use 12-24 volt LED bulbs which are brighter in a small form factor that will work in either receptacle, the LEDs will be plenty bright enough.
If I want to cannibalize the female plug on my FLU 419 SEE, I could make an adapter pretty easily, but I like the idea of just plugging into the wiring harness in the junction box with my own adapter. I have not sourced the barrel connectors yet, but there are several on my SEE that are in very marginal shape and should be replaced.
I will post my final solution when I have it.
Thanks to all that contributed to this thread.