Formula for strong but lightweight paper-mache I've always used the standard flour+water = paper mache. This often results in a somewhat heavy and fragile object though.

I'm looking for a formula for a strong but light weight version. Light-weight being key.
I'm hoping to create a scaffold of chicken-wire and mache over it to create a smooth surface.
I've also read that using "blue shop towels" can be better than newspaper so that is what I'll do.

The end product will be moisture-sealed and mounted to the bathroom wall to hold toilet paper in a decorative way (think "giant sheep" or some other fun shape that involves toilet paper rolls).
I've always used slightly diluted white PVA glue (just enough water to make it runny enough to soak paper in). Recently tried using kitchen roll, which was durable and held its shape well. Tissue paper (as in artistic, not toilet roll!) is also nice - very lightweight, and can also go directly on top of chicken wire, if you preferred to make a framework with the wire. Careful if you're using dyed paper though; sometimes the colour leeches out of the paper, or just runs everywhere. 

EDIT 

Hopefully the photo shows it a bit more clearly. It's pretty tough, and holds paint really well. It smoothed fairly nicely, but we were in a bit of a hurry (and the bobbly texture actually worked quite well with fruit!)