There are federal laws governing, and the legal wording may vary from state to state compounding the responsibility of, but basically as I understand it, only a registered manufacturer may assign a V.I.N. to a vehicle intended for the registration for use on public road systems; and it is looked upon with negative connotation if a person should invoke the terms: knowingly, "to taper with", "altering", "obliterating", "removes", or perhaps in this case "affixes" of such V.I.N. identification, which I feel would include from one vehicle to another, or even creating ones' own (repop plate), perhaps except, with provisions by the individual state, permitting a "Homebuilt", and this is generally identified as such on the title.
Now, for "Off-Road Use Only", have at it, as it is at that point defined only as a piece of "Equipment", not a "Motor Vehicle". But, about that title?
And, just because someone gets by the local D.M.V. and has a title in hand which may state such, does not make such truly fact; example: how many Cobra kit/reproduction/replica/continuation or whatever are there titled and registered as 1965's even displaying "Antique" tags, and are obviously far from it!
Scott.