When we bought our boat in Brunie we registered it in the Cayman Islands
. The transaction occurred at sea so there was not VAT or GST anywhere. this is in fact quite common.
If I had to do it all over again I would register the boat in Malaysia
which has no duty as long as the home port is Langkawi or Labuan. There are no annual fees
and from what I understand this might prevent the US government
from boarding your boat anywhere in the world that they feel like which they have the right to do if you are registered with the USCG.
There was a thread on this forum that you could search which was I believe titled "registering a boat in Langkawi" for more information.