hello, it is best to get a sparky to do the brake controller, i had a 150 kakado last year, they do run a small computer board in the rear that runs the trailer plug. in there is the blue wire that runs to the brake controller, you also will find the breakwire that runs to the trailer plug, this also runs to the break controller. as for the 6mm cable for the fridge, you might be better running a thicker 8 gauge cable from the battery to the rear, this will run the van and the fridge at the same time and will give you less trouble in the future. sometimes 6mm cables are not 6mm cables and area all plastic - not copper. also some fridges need more power to start them, and 6mm will somtimes throw a error code on the fridge on startup - meaning you have to reset the fridge for it to operate again. also the negative running to the plug and the fridge can be short and connected to the chassie. (make sure you take the paint off the chassie before connecting the eyelet) doing this will further reduce voltage drops to the rear.