Canuck,
The cable between the monitor and the battery/shunt can be very small. I prefer to run what is called 2 shielded pair (a cable with 2 pairs of conductors and each pair is individually shielded) but I have also used a single run of telephone station (4 conductor any tiny) with reasonable results. As your trailer does not have an engine to add electronic noise, probably any four wire unshielded cable will do. You can actually bury it in the molding or edging of the interior panels.
The Victron only uses RJ47 station cable. That can be hard to put through small holes unless you have the tool to put the ends on. I am not sure why Piano thinks it is a better instrument. They both give you the desired information.
I happen to like these things alot, but we only got to install a few of each before the depression killed our company. But I did put one in my coach/office/tool crib.
Matt
