How to add import duty to international orders?

I suspect this isn't possible without some major coding/changes, but...

I want to start offering DDP service to (initially) EU. (Delivered Duty Paid)
I would need to add a handling charge to cover the carrier's fee, but that ability is built in to the zones module anyway.
However I cannot find a way to add the import duty to the order. As the majority of my products are the same HC code (and can all be classed under the same code for convenience if necessary), only one rate is required.

There is another issue in that duty will only be chargeable over a certain threshold, but sorting that will first need to know how the duty charge is implemented.

Unfortunately the handling fee in the zones module cannot be a percentage, or I could have used that and just added the actual handling fee onto the shipping rate. I'd have needed to produce a new itemised invoice for every order, but it would have been a relatively easy solution.

I can't find any modules or any forum posts/solutions about collecting duties, so I realise this may be a long shot.

You're going to have to write custom code to your specific requirements.

I'm pretty sure you can do whatever surcharges you like with whatever limits you like in the commercial plugin Advanced Shipper. If not, you can customise it.
I've always used it.

Any questions about Advanced Shipper should be of course to the supplier, but further comments or queries to other users about it should be in this dormant thread
https://www.zen-cart.com/showthread.php?157585-Ceon-Advanced-Shipper
which is the first that comes up in a search/as good as any to re-activate.

Thanks for the replies.
I am wary about using commercial modules when there isn't reliable customer service and from what I've read on here the CEON modules don't have the best after-sales service recently. Plus I'm planning an upgrade to 1.58 soon and no idea if the module will be compatible.

Valid points to make in that thread...