My two cents...
The powertank is super convenient, but bulky. There are many smaller options for airing up.
Kids are in the back seat, and their legs are short. Put stuff on the floor, the kids won't mind and it's a surprising amount of space.
Use the whole space behind the second row of seats. This requires a cargo barrier, but the advantage is that it allows you to fill the entire rear cargo space. It's a huge space, if you can use the whole of it.
Use a roof rack for light weight stuff (clothes, sleeping bags, etc). This won't affect your COG at all, but will give you lots more freedom inside the truck.
The single most important piece of advice - bring less stuff. Some Africans can walk 100 miles with their entire endowment in their hands. I couldn't do that, but they are an inspiration.