We've been having these meetings for a couple of years now. I can't recommend it enough.
There is a camping “toilet” made by Pett http://www.thepett.com that is pretty spiffy, a pop up tent is supplied. The business end consists of a sealable bag and some type of enzyme to breakdown waste. It all breaks down into a compact package that fits into a self-contained backpack. Not a pleasant topic especially, though one that is important to plan for.