Its a game of straps on those flat framed twin tube barges. I suggest lots of loop straps and figuring out a system that works for you. those boats can be fun when not overloaded, as they are nimble and crush big whitewater. I remember the large square vittle vaults did pretty well sitting between the tubes with one strap over them for securing dry storage. There are a lot of cool things you can do with them but the reality is they dont carry a lot of gear well.