I've also added the mk1 camera cube for trips where I take a lot of camera gear.
Just be aware the company is REALLY slow to ship... Like, TRAGICALLY bad... I had to wait months each time I've bought stuff.. That being said though, I'd wait again... And I'm about to buy a new prima system as this one is getting old (after many years of EDC) and I'm looking at the XPAC version.