I've seen a similar home brewed shroud made from a big cookie sheet, with a couple of rubber ram air flaps to allow air to bypass the fan at highway speed. If there's room for it, a thermostatic fan hub can be adapted to the water pump to minimize noise when the fan isn't required for cooling. That system is totally mechanical, no electrical hookups at all.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!