I have a party-wall in my apartment-née-condo that seems to have two sheets of drywall installed against eachother. All attempts to find some sort of stud or resilient channel / furring strip have failed miserably; short of going Hulk and tearing out a hole large enough to stick my head in and look for studs, I've given up. (And I don't have the drywall-repair skills to seriously do that; if it can't be repaired with spackle, I'm not going to try it.)
I've looked at quite a few anchors; but most (toggles, mollies, and the like) of them seem to assume a standard(?) 1/2-inch thick sheet, or so. All the ones I have certainly do. I don't want to fall back on using plastic-expansion plugs, if I can avoid it; I hear they're extremely unreliable.
Does anybody know if high-shear-capacity drywall anchors exist that latch onto double-thickness drywall? Or have other advice for me?
(For context: I'm installing a large shelving system, that should ideally be able to support quite a bit of weight.)