I'm not clear on what that last question was, but here.
Admiral MS's shipsave script doesn't save anything to variables, really. It saves all the data to a file that it creates. So variables being campaign or player persistent in this case do not matter. You simple direct the shipsave script to the right file to load data from any point in time. Heck, you could save data in a mission in one campaign, start another campaign and load that same data there, all without the use of FRED variables to save any ship data.
You could do this in FRED variables (I'm pretty sure BP R1 and R2 did just that), but I see little point when this script is far, far superior and easier.