First of all - welcome to the forum Scamper! If you have a sec - come on over to the new member area and introduce yourself.
As far as the tank - I don't have a 23FB, but I have to imagine mine is similar. I have two small drain tubes that extend down from the tank and handle the overflow. They are very obvious and are near the low point drain.
Some people have complained in the past that they loose water during travel out of the overflows and they cap them or do a modification. It is possible that is what has happened in this situation so I would crawl on under there and look closely for evidence of the two tubes.