Build your custom field gear around your equipment. That's how I did it. I ruck has to be able to stand up on it's own, like the large alice pack. See if you can build some of those new packs to fit on an alice frame. And put some rollerblade wheels on the bottom so I can use it as luggage thru the airport, a pull up handle too maybe?
Have different mounting points on the straps so that different size guys can custom adjust it to their height.
I like to have quickie access to my water and my snacks while on the move.
the PRC-77 , claymores, a little C-4 and extra batteries. will take up the middle of the ruck , build the pockets for me and my stuff.
A big mesh net pocket on the very top to stash my wet goretex jacket or poncho in.
I'll think of more later...