Using -'e' on the head noun of a relative clause is entirely optional,So, if a potentially ambiguous relative clause (not only in a noun-noun construction) is in context clear or if I don't want to disambiguate it for whatever reason, I don't have to place *-'e'* in the head noun (but I can always do it if I want). Have I understood it correctly?
Correct.
By the way, I know there are canonical examples of noun-noun constructions with noun + adjectival verb, but are there any canonical examples with a noun-noun construction containing a noun + relative clause?
Yes.
romuluSngan Sambogh 'ej HoHbogh nejwI' Romulan hunter-killer probe (STK)There are undoubtedly others.
-- SuStel http://trimboli.name