Lock some calipers (with a rod sticking out) to 1.5mm shorter than the part height, compress it down onto a kitchen scale until the rod is just touching the platform, and record the weight.
That's just the first procedure that came to mind. I will try to think of a way to do a hook strength test today.
I just tested this hook by hanging a 5 gallon bucket and gradually adding water. PLA 1 wall = 1710 g, 2 wall = 1178 g. The thing is, a 1.5 mm hook fails by straightening rather than snapping, so rigidity is more important than strength.
Edit: I also tried PETG: 1 wall = 1441 g, 2wall <998 g (failed to hold the empty bucket)
So the 1 wall hooks can support >40% more weight before straightening enough that the bucket slips off. That's more significant that I expected.
Edit2: Part of that 40% difference is due to friction; the 1-wall hook has a rough surface that makes the bucket less likely to slip off. But even with bluetack on the hooks, 1-wall has less deflection than 2-wall for the same weight.
Another confounding variable is the weight of the hook itself: 2-wall = (0.83g slicer, 0.78g actual); 1-wall = (0.95g slicer, 0.88g actual). I don't know if that extra weight is coming from density or volume, but either way the stronger hook is more expensive.
Sigh, reality is so complicated.