Yes, the Saab had the engine reversed (belt against the firewall) and only an electric fan. But if you lose the belt-driven fan, you may be able to fit an additional electric fan behind the radiator, if you need one.

I wouldn't worry very much about the weight of an electric fan. I'd worry more about the load on the crank of the mechanical fan (or the alternator, if the fans are running before you need them).