(We never stop thinkin')
Here is yet another thought because you have access to pipes limited your your TM model:
If you do want to run a tube out the bottom or side -
you can eliminate the valve on the tank drain (far left on picture in previous post).
Use my 2nd idea in previous post to run outside shower into bucket fill port.
Connect new outside pipe to input of water pump. (with a tight cap on outside end for normal TM use)
You will only need the one valve now -between output of the tank and input of pump.
This also means only one pipe to cut inside to add valve and new pipe end.
Finally learning to use MS Paint:
http://i849.photobucket.com/albums/a...pesusing-2.jpg Diagram v3
..