If your stock shocks were keeping your truck from going lower, you would know it as your shocks would be bottomed out making for a very rough ride. On the other hand, the shorter shocks might work like limit straps, limiting the up travel of the rear end. But again in order for your springs to fall out, your rear springs would have to be fully unloaded from the trucks weight.
Sorry I think what I said was confusing. I didn't mean that the shocks might be bottomed out, but that they might be "pushing" up a little(raising ride height) since they are made for the truck at factory ride height(not with 1" or 2" lower springs).
And that's what I was thinking about the shorter shocks being like limiting straps. I might look into this/try this once I need new shocks, which will be soon.
Honestly the springs falling out is a big concern to me, I believe I've hit some railroad tracks that have pretty much completely unloaded the rear axle. Not that I'm doing jumps or anything, but it is a concern to me...