g450, can't help you there, we are UK based. I am surprised though that the handlers can't guide you, they are responsible if you as a non-UK operator fail to register. The HMRC is pretty clear on that one, if you don't pay, the UK handler is liable.
to quote the HMRC:
If you fail to appoint a fiscal representative we may make your handling agent jointly and severally liable for future debts.
Try some of the bigger handlers here, LTN/FAB and see if they can steer you in the right direction.
There are quite a few handlers who post here so one of them may have an answer for you.