There have been quite a few posts lately regarding Zodi's camp-shower
products.  I bought one of their portable hot-shower units last summer and
thought I'd post my experience.  The type I bought was a stainless-steel,
jazzed-up version of a garden sprayer.  The top is removed, the tank placed
on the stove, and the water heated to the desired temperature (a crude
thermostat is on the side of the tank).  Problem #1 for Westy campers is
that the tank doesn't fit well on the Westy stove-it is too tall and must
be placed in such a way that the tank only overlaps about half the burner. 

When the water is heated to the desired temperature, the top is attached
and the tank pumped a few times with a hand pump (just like a garden
sprayer) in the top.  This allows hot water to be delivered through a hose
and sprayer.  This part works fine outside, hard to do inside the camper on
a chilly day without soaking a goodly part of the interior.  

All in all, we found it didn't work well for use in the Westy because of
the poor fit on the stove and its overall bulk.  Space is always at a
premium when camping in the Westy.  It was also very expensive-around $100
if my memory is correct.  Zodi has other products which use a coil on top
of the stove which could be connected to the faucet-this may work better. 
I suspect a hand-built arrangement (some clever ones have been described on
the list) will work better than anything that can be bought off the shelf.

Bill