I use virtual servers based on Porteus for some time now.
They have 000+001 in base and rc.sshd,rc.font,rc.keymap in rootcopy (and empty /etc/issue file to better see boot messages)
Servers that are working at the moment:
xmpp (prosody + lua)
http(s) (nginx + php + misc) (sometimes php-cgi process crashes and I have to restart it)
domain controller (samba4 + misc)
old fileshare (samba3).
I can upload them (stripped of private data) somewhere if this will help. They're far from being ideal, but they're working.
Here's my 2 cents (although I think this is mostly relevant to virtual servers):
I check sda1 for necessary files in rc.local because usually that's the only drive I add to my virtual machine. But checking for drive label would be better IMHO.
Main reason for me to use Porteus as a server is the fact that it consist of archives and a bunch of configuration files so I'm sure that only these config files can be the source of the problem. And to prevent further problems I use ISO files.
Sometimes I add checks in rc.local to execute commands (also for ssl certificates and to copying additional files from /conf/rootcopy) from "/mnt/sda1/conf" to be able to tune server in the future. This way in case of problems I can always wipe data disk and get fully operational clean server. Probably checking for partition labeled "config" would be better...
Suggestions/corrections/additions are always welcome.