I, too, am "in the heat" (Memphis) and have been looking into electric fans for my 545. I have pretty much decided on the Lincoln Mark VIII. I understand that puppy moves some serious air and can be had for a reasonable price - - goggle it and you will get all kinds of responses on ebay and other places.
From reading about it on different forums, it apparently requires some heavy amps so I am going with a 140 or 200 amp alternator. Using the Lincoln Mark VIII should negate the need for a mechanical fan, IMO.
Hope this helps!
BT