DC to DC charger - Hilux

Hi all
I have just purchased a brand new SR5 Hilux.
My question is, i have installed a 2nd battery in the ute (not wired up yet) & i will be towing our Kimberley Kamper with it.

I have heard the Hilux alternators dont provide enough charge to 100% charge the 2nd battery. I see Ctek install a Dual DC to DC charger. thats fine.
But CTek say to install this as close to the 2nd battery as possible, no worries.

My problem is, I also want to charge the two deep cyles (200+amphr) batterys in the camper.
Can anyone tell me where i should install the DC-DC charger?
Should it be in the camper closest to those batteries, or still under the bonnet near the first dual battery?

Also, which charger exactly would suit best?

Any help greatly appreciated
Regards
Josh