best way to manage 3 batteries?

[POD]

I have an auxiliary battery in the Defender which is managed by a fairly old Pirhana dual-battery system. I'm now adding a camper with it's own battery running a fridge, HWS, diesel heater and lights. I plan on continuing to run the Engel in the vehicle as well as the camper's own fridge. I'm wondering how to keep the camper battery charged whilst travelling- I can hook up solar when parked.
I have an Anderson plug at the rear of the vehicle which is connected to the auxiliary battery and there is an Anderson plug on the camper connected to the onboard battery. Would it be sufficient to connect the camper into the existing auxiliary system, or do I need some additional management gadget? Aux and camper batteries are both AGM.

[Narangga]

I used a Traxide kit to handle that for me and it gave me an additional outlet inside the vehicle too.

[jerryd]

I've got two leisure batteries that are wired parallel that go through a dc-dc charger, they are fairly close together and the cables would be no more than 400mm long.

I'm not sure what the maximum distance between batteries would be before they'd be affected, maybe ask an auto electrician

[Tombie]

If its all AGM dont overthink it...

My previous configuration in the D4:
- Primary AGM
through Traxide USI160
- 2x AGM underbonnet aux
through Anderson connector to Van
- 2x AGM 110ah house batteries

And guess what, it worked perfectly.

[W&KO]

Don’t need to do anything….just plug the trailer in.