From what I've been told by the Rhino dudes, it's squadron SOP. Some skippers prefer to have one or two jets designated as the permanent tankers, others prefer flexibility. I think a lot of that stuff is still being figured out by the community at large, and it's going to get even weirder in the coming years as VAQ gets into tanking and the Hawkeyes show up with their refueling probes.
From watching the guys do it in the hangar bay, it seemed like hella work to move the tanker pods between jets, and not something to be done if you had a choice.
CAG still hates it when the Rhino guys run out of tankers.
Probably ain't gonna happen - probably.
Brett