Yep. I could mount knoppix UNIONFS and ramdisk with your methods.

But still have a problem.

I made some files on server, and exported /testroot.

ex) touch /home/knoppix/test

As U know, executing above order /UNIONFS/home/knoppix/test and /ramdisk/home/knoppix/test are created.

But I couldn't find my files on client knoppix.