Guatemala - the port captain screwed us for an enormous amount of money to be allwoed to anchor for two days. Weather outside was nasty and I had a seasick kid so coughed up. I enjoyed the place and the people but that left a bad taste. Puerto Quetzal on the Pacific coast.
Register in Langkawi, sail to NZ, re register here if you feel the need (I wouldn't bother - cheaper if you ever decide to do a trip up to the islands one winter).
Anyone can register any boat in Langkawi - around $500.
I vaguely remember there is some rule that if you are bringing in something for personal use that you have owned for a while then no charge, but I could well be wrong, never done it, but I seem to remember car people bringing vehicles back.