Towing a caravan with 60 series Toyota Sahara 4WD

Great combination and hard to beat. I would get some some of those stablilisers that fit onto the drawbar and towbar and some wind deflectors on the bonnet just to make it tow nice. Snorkle is not compulsory but does help to get cool air into the motor.

Mate that would haul the van ok, they have the best donk that Toyota ever made. With the trans cooler you shouldn't have any probs, I've got a mate with one and the only time he has had any probs was when he was pulling his camper in soft sand for a whole day the trans heat light came on so the cooler should solve that problem.
I take it is 24v, most of the grey imports are.
The best way to run 12v accessories from it is to fit a Redarc charge equaliser across the two batteries,(www.redarc.com.au ) this will keep both batteries at the same charge level when you take 12v from one or either of them. I've had one of these units in my truck for 18 months with no probs. I've got a HF, CB's, AA battery charger, inverter, GPS, stereo, mobile in car kit and a frig running off 12v with absolutely no problems.
If you have to buy a frig get one that has the latest Danfoss compressor in it as they will run on either 12 or 24v, 24v is much better as the current draw is halved.
I know my Autofridge will run on either 12 or 24, it took me 18 months to get around to running a wire to it with 24v, in the meantime it ran on 12v. But it works much better on 24v, don't need auxilary battery either as the current draw is only around an amp.

Douglas
The reducer is not the best way to go as they are basically a 24-12v transformer which has quite a bit of loss in it. (uses more power than required with straight globes)
The same applies to the reducer which goes into the trailer wiring which allows a trailer/van with 12v lights to plug into a 24v vehicle, not the most efficient way to go.
That is where the charge equaliser is the better alternative, it just sits across the two 12v batteries and keeps them at the same state of charge regardless of what 12v accessories you connect to them.
The best way to overcome the 12v trailer is to change the globes to 24v, freely available at good auto parts stores. If the trailer/van is towed by a 12v vehicle occasionally just change the globes back or alternatively fit new LED lights which can work on either voltage a much better but more expensive solution. Also the LED's are usually waterproof, last longer and are amuch tougher unit all round, a lot of trucks are running them these days rather than globes, less power drain, tolerate poor connections and need smaller wiring.