Question Domains with no hosting in the same subscription

[onlygio]

I have a bunch of domains I will be park, no hosting needed, only mail and dns.

I was figuring if I can change the courtesy page of each domains using a script that run in a website domain of the same subscription.

This script read a db to show some text.

The only workaround I found is to set the domain like website and assign the same root folder for all.

I've added more than 400 domains with no hosting, and I don't really want to change every single domain

Thanks in advance
G