There should be no reason for you to sneak a WC.Start a syphon and put the output in your toilet.The bowl will stay the same level,as toilets are self-leveling due to the one way routing on the toilet.Even if you dumped a full 5 gallon bucket into your toilet it would keep up. As above suggested,cycle your tanks,cut down on immediate feedings and change your water.A five gallon poland spring jug is good for this.
