Thanks, that's exactly the arrangement I am planning. As you say, number one priority is to be able to start the car and my Traxide should then shunt the extra power to the second battery no worries.
I just need to sort out drawers for the Defender and then I can mount the second battery permanently.
I have a set of folding 80 watt panels which I use with the camper but I will add an Anderson plug to the second battery in the vehicle so I can also charge it with them. Later, I intend to put a modest sized solar panel on the roof rack and connect it down to the first battery.
With a Matson DC charger in the camper fridge box making 20 amps it will mean I can charge the camper fridge battery either/both with the solar and by plugging in the trailer plug and running the vehicle. Gotta keep the beer cold!

