Brake Controller
I can only speak from personal experience with the brake controller, and my experience was NOT a good one.
I had one of these Redarc supposedly proportional brake controllers fitted to my Commodore. It was anything BUT proportional, I had to adjust the braking power myself as I was stopping and that was too much for me. It went with the Commodore when I traded it on my Navara - and I asked the Nissan dealer to fit a proportional controller. They sold me the Tekonsha Voyager.
The Voyager IS proportional, no doubt, but its inclination adjustment is manual. The documentation for the controller tells you to adjust it on level ground (which is the advice for any controller) but when you are descending a hill, the sensor thinks you're braking already and a slight touch of the brake pedal slams the van's brakes on and the opposite works up a hill. That's really something to get used to.
I've removed the Voyager and now have a fully automatic Tekonsha Prodigy P3. Doesn't matter about inclines, I set the power level depending on the terrain (eg I turn the power down when towing on muddy roads) and then forget it. The van brakes perfectly under all conditions.
Deep Cycle Battery
Over a long cable run, the voltage on the end of the cable is significantly lower. Batteries need a decent voltage to ensure they're charged - the typical 14.3-14.4V found coming from a car alternator is enough to roughly 70-75% charge a battery. To fully charge it, you need more.
You fix this in one of two ways. The more dangerous, yet clever (because it disconnects the fridge and unloads the battery for a perfect charge) is to use an inverter in the trailer and use a mains charger to manage the battery (the inverter should also be large enough to drive the fridge at the same time).
The safer way is to use a DC-DC charger like the one Redarc sell, or the D250S from C-Tek (which also has a solar input - something you really, really might want to consider). These DC-DC chargers take a lower, possibly fluctuating voltage and boost it enough to provide a decent charge rate for the battery. They do NOT unload the battery by making the fridge flick to 240V, so they aren't going to get a clean look at the battery condition, but they are far, far superior to the old isolator-and-hope method.
I'd also recommend that power to the rear be fed by a relay, not direct. The relay is activated by IGNITION on (not ACC on) so that it's only really on when your engine is running.
