hate to state the obvious. go and fix the cause of the problem. I had overheating issues with my EA82, I did everything I could to overcome it, flushed radiators, replaced water pumps, wired up the fans together. in the end, I blew a radiator hose 200 kms from home. the cause? a radiator which appeared to flow ok, but was full of ************e. had I bit the big one and took it to a competent mechanic, paid the few hundred dollars to keep him in a job, I wouldn't have had the headaches, or made myself feel like a tool for not fixing it properly.
by the way, I wired mine up to the spot lights wiring, disconnecting them, but it was an emergency measure which got me home. surely you could parallel them to the first fan without causing problems