pool heating

[beachfrontpool]

We gave up our gas heater just before winter, as beachfront wear and tear rusts them out regularly. After a winter of being unable to use my pool (just too cold this winter in central Florida), I am anxious to investigate alternatives for next winter that would wear better on the beach.
I came across this idea online: someone took a truck radiator, painted all the fins black, and put it where sun shines most of day. A 1/2 inch line was put on the discharge side of filter pump and run through the radiator. A faucet (I assume that means a valve) was put on the line to reduce or stop the flow. This method was used on a 20' x 40', 11' deep end pool in the midwestern US. They stated that it heated pool so well it often had to be shut off. Even on a a cold sunny day, like late September, it warmed the pool enough (82 to 84 degrees) to last for late night swim. The owner also had a gas heater, and stated he seldom had to use it as a booster to the home-made system.
It's much warmer here in central Florida (with lots of sun), and this seems a simple, elegant, and low cost way to warm up my pool in the winter. What do you think?