Setting up a read only system

I'm trying to configure a system that is completely read-only except for a secondary hard drive for data. I've changed /etc/fstab to have "ro" instead of "defaults" for the specific partitions. I switched /etc/sysconfig/readonly-root to have READONLY=yes. I've also added a few entries in /etc/rwtab to allow writing to a temporary file, mostly for logging so certain services can start. However, after making these changes in read/write mode and rebooting, I get multiple errors on boot about services failing to start and have to edit the grub menu to change fstab back to read write to log in. Has anyone attempted to do this and have any ideas? Thanks!