I do not need extra config.xml files as the products in the storeviews are identical. It is only the language that is different.
The problem is that the value set in the backed for The Master Config URL (PRO) will be paste at the end of the URL.
In my situation I have a dutch view with storecode NL. It will generate the URL https://www.papegaaienzoo.nl/webshop/nl
The 'nl' is virtual. It is not a physical folder on the webserver.
When opening a productpage, the adhoc plugin will load the config in https://www.papegaaienzoo.nl/webshop/nl ... config.xml
and this will end in a 404, because the config.xml cannot be found in that folder.