Write a cronjob for vhosts on wheezy to run logrotate as the vhost user
If the vhost doesn't have a custom vhost file, write the default one in the vhost's root
Generate a single logrotate config file for vhosts that don't have their own custom one
Use a vhost-specific down.html if present in /data/servers/vhosts/downs
Add a private site down.html fallback option.

So vhost www.example.org, using site example, would try in order:
vhosts/downs/www.example.org.html
vhosts/downs/example.html
repo's web dir as per usual.