Re: Trailer lights from new boat not working...
daddie(not sure how I feel about saying that to you but ok...) where are you? and what is your mechanical background? are you somewhat handy or definitely not?
The reason I ask this is because first, if we knew where you were we may be close enough to help you personally.
Second, the way you are troubleshooting makes me think your not the mechanical type of guy, I could certainly be wrong but we don't know each other and please don't be offended.
and third has the boat lights ever worked on the range rover? Or is this the first time the boat has been hooked to the Range Rover? The Uhaul is good info but only to a certain point, we know the plug had voltage to it then but now we don't know for sure, the Range Rover plug could also be wired differently then the boat plug which is most likely the problem you are finding, further, if the plugs are wired differently you may have blown the fuse in the range rover trailer package.
To properly diagnose this you will need a DVM (preferably) or at the very least a test light, do you have either?