Knoppix 5.3.1 Remaster

I know this relates to an old version of Knoppix, but after remastering the os and upgrading the kernel to 2.6.31.6 (and compiling aufs as part of that) i'm not able to remount the /ramdisk branch as read-only upon boot. Or after in init 2. If anyone can advise on this, it'd be much appreciated.

When running the script below:
/usr/sbin/knoppix-image /mnt/sda1/knoppix.img

The following line is failing:
mount -o remount,noplink,prepend:/KNOPPIX.IMG=rw,mod:/ramdisk=ro /UNIONFS

The following line succeeds fine:
mount -o remount,noplink,prepend:/KNOPPIX.IMG=rw,mod:/ramdisk=rw /UNIONFS

I get mount: /UNIONFS is busy error.

I've deleted whiteout files on /ramdisk beforehand with:
find /ramdisk -iname .wh.\*.plnk -exec rm -Rfv {} \;

I've run fuser -m -v /ramdisk and used the -k option to kill processes off.

I've also run lsof /ramdisk and killed associated processes.

Distilling the command down to the following fails:
mount -t tmpfs -o remount,ro /ramdisk /ramdisk

The following command succeeds:
mount -t tmpfs -o remount,rw /ramdisk /ramdisk

In /etc/mtab /ramdisk has mode 755 0 0.

If you can help please advise.