... Very seldom has anyone queried that the registration
expiry date on the papers states 2000. When they have, I merely say
that in New Zealand the original still stands and that I have some
documentation somewhere on the boat to show that it is still current.
A lie perhaps but why should I pay the $1,000 or so for registration
for another 5 years. ...

You may get away with this, and 1k seems wildly expensive for
registration, but not everyone who tries this has as much luck as you
have. I have witnessed folks getting into very uncomfortable
situations with customs because of lapsed registration. In the
islands there is always the temptation to just sail away but that does
tend to poison the waters for folks who follow on and even the most
primitive customs houses seem to be able to forward the particulars of
offenders on. French and US territorial folks do not seem to care
much but the Aussies and Kiwis do and it can be awkward to have to
fight the government in either of those places. I don't know how it
all plays out in the rest of the world, but since US renewal is free
and since they will send you a new cert any time you ask for one I
haven't ever been motivated to go without.

-- Tom.