If I understand you right you are blaiming initscripts with daemons that log to something like /var/log/$FOO/bar.log and complain if /var/log/$FOO does not exist? Well, that's something you cannot work around that easy...
Oh, I wish they would complain! They just fail mysteriously! But yes, that is the idea. Our shortcut was a master /etc/init.d/tmpfs-prep script making fresh directories for broken init.d scripts.
The real answer is for script authors to write defensive code. Init.d scripts already conform to a certain style convention so it should not be hard. These days of multi-gigabyte memory means running from RAM will get more and more common. For us, there is no reason to slow down apps with unwanted disk access just because some init.d scripts are sloppy.
"Mounting an empty directory through tmpfs" to something like /var/log has to fail if you don't take further actions. Ah, looks like you are searching for overlays via unionfs. :)
Not clear what that means. Here's what we want: small system directories causing frequent disk access and opening security risks mounted in RAM.
M