Old water heater as solar water trough?

So I've got an old hot water heater tank I need to get rid of and I was searching around for ideas.

Then I remembered an old article on Build It Solar (picture below) where someone insulated a stock tank so their animal water wouldn't freeze in winter.  Just thinking... a water heater's already got great insulation...  hmmm...


Do you think it's possible to achieve the same thing by splitting a water heater lengthwise, then cut off a section the outer jacket on sunny side and paint it black?
Probably add some feet and viola, 2x freeze-resistant water troughs for basically free!

Bonus question:
Supposing this works, how to adapt one of them for chickens, so the dumb birds don't jump in and drown?

Folks around here grab up old water heaters to make smokers for BBQ.