used that one before, in Citidel Hotel.
and, yeah, if the hole is too shallow, the water will be sort of traffic jam when channeling through the pipe, only 3 cure i can think for you:

1. not to do big on that
2. change a higher bowl
3. cover the bowl when flushing

PS: i saw some home toilet they build a "stage" and keep the bowl high...
maybe you can do it without hacking the tiles ..... by adding heights on the base of the bowl

This post has been edited by 9876789: Jun 30 2011, 07:01 PM