@harpo75: There is a way to use the VSS Double Pocket sleeves on a triple gatefold jacket, I’ve done it.
You put a Double Pocket sleeve on both the two outer gatefolds, with the tape strips on the flaps on the back of the jacket (you MUST use the version with the tape on the flap, rather than the body). But before you put them on, take a Multifunction sleeve, cut off both flaps (I lay a sleeve down on cardboard, place a straight edge across the sleeve right where the flap meets the pocket, and slice with an Exacto knife), then slide the sleeve past either of the gatefolds until the sleeve covers the middle section of the jacket. Then secure the two Double Pocket sleeves to the Multifunction sleeve with the tape strips on the flaps. If you don't want to cut off the two flaps on the Multifunction sleeve you don't have to, but in that case the sleeve must be used with the flaps on the inside of the gatefold jacket.
You then have a pocket on the inside of the front gatefold for one LP, and a pocket on the inside of the rear gatefold for the second and third LP’s. That might sound confusing, but once you have the Double Pocket sleeves in hand it will become obvious.