Hey there Kat
The boys down my way are using the twin electric fans & suround of the EL to BF Ford Falcons as they can have the first fan hooked straight to an adjustable thermostat & the second fan to a switch inside the cab & after cruising with 1 of them it seem to work very well as they only realy use the inside switch when towing in heavy traffic or up very long hills... This maybe a cheaper fix for you just get 1 from a wrecker
Also just fixed my GQ 2.8 heating problem, ripped the head off to find the multi-layer head gasket had cracks through a few layers but not right through, replaced gasket n now it doesn't get near half way even with trailer on. Mine was heating up under boost pressure spitting boost through the cracks pushing water out of radiator then running round town with no high pressure it was drawing the coolant back into the radiator done this for 2 years then I got sick of seeing the overflow bottle full after a trip & no-1 could tell me the problem, thats why I did my own investigation n found the gasket problem. All great now done couple of trips up in the hills & getting way better economy & power now.
Hope this may help some-1 over time.
Cheers TonyD