Ex US Shipping Zones... Now what?

Hi all, I know the question of how to setup Shipping Zones for countries other that the US has come up before. I appreciate the answers that have been given however I still need a solution to the problem now without having to wait for Squarespace to prioritise it.

I need a real simple solution : For delivery zones, by post code or radial distance from a given point (don't care), charge $x for delivery, otherwise delivery is free.

I'm interested in hearing from anyone that has solved this and how. I'm happy to hear any solution. Things I've thought about but haven't tried :

• Use Amazon Self Ship and integrate that via Shipstation
• Build my own simple shipping calculator service and integrate it with Squarespace

I am developer by trade and happy to be told RTFM, just point me in the right direction.

Squarespace checkout is completely untouchable, so every manipulation like these are simply impossible. 

I thought about the Shipstation+FBA combo too but we are worried we may lose the contact with the customer. Moreover, it is likely that the customer will decide to buy on Amazon rather than on our website. 

Once again, we have to wait for Squarespace... that sucks