I understand the brakes each need a wire for 'positive' and each needs to ground with other wire. I'm wondering..do I need 2 junction boxes about mid point and cehter of trailer- one for 4 grounds to go into and one coming out and going to front..then the same with the positive- so I'd only have two wires at tounge when wiring plug? and of course my light wires too. I heard best to keep all wires equal length? is it also better to run ground up front..or could I ground it inside junction box before taking it up to tounge? pic's,pic's please.