Any tips on the best way to configure Amazon Prime Video to work ok a Fire Stick?

This partially follows on from this thread

• https://www.geekzone.co.nz/forums.asp?forumid=151&topicid=251493

I've got several Amazon accounts due to travel and various overseas orders.

• primary account is set to the US for devices as I use the US Kindle store for book orders.
• secondary account I've used for FireTV devices in the past so I could change regions and load US and UK applications

I recently had a UK version of Amazon Prime active on my primary account, and streaming worked while I was in the UK when I registered a FireTV to this account. Returning to NZ Amazon prime showed as active but streaming wouldn't work unless I initiated the stream off my Android Tablet.

Web based streams and using the Android APK worked, but the FireTV consistently showed error 5005.

I don't want to screw up the region settings on my primary account as last time I changed anything it broke my household settings and I had to spend an hour on the phone bouncing between Amazon regions to resolve it.

If you've got Prime Video (not Amazon Prime) working on a Fire TV what is your configuration?