some of those can do jump starts as well, but i do not need that anymore i think. Still bring starter cables just in case.

Bison Smart Battery Box BISON - Decathlon

With the Noco, I was just thinking to power some USB LED strings lights and to use as a power bank type thing and hopefully have enough left for a jump-start. Any thoughts on these options or any I have missed? I would welcome comments from seasoned campers. Suppliers/Dealers or anyone selling with a commercial view in mind CANNOT post here unless responding to a specific request of a member in a "wanted" post.A secondary battery i think is the best option so far. My dash cam would recored for days on end in parking mode. No need for a Noco or similar so that would offset the 2nd battery cost. In the Gen 4 I think room could be made by relocating the washer bottle over to the bulkhead and putting the 2nd battery in its place.

Bison Smart Battery Box with 4 extra USB outputs BISON

I installed an 45Ah LiFePo4 battery as primary battery and moved the original battery into a second tray. Like you say a battery box would require some memory to remember to charge it or keep it connected to a battery conditioner. But you are only carrying when needed. I just enlarged the original battery stand and squeezed a 70 Ah AGM battery in there. No more problems in cold weather, never worry when the lights are left on. and just a large USB battery bank for stuff that needs charging on travels.Probably have the same power as a secondary battery, but only need to take it when out on an adventure, not all the time Where you have relocated the washer bottle is like what I was thinking for the Gen4 although it looks bigger 4 liters I think it is?