Besides what Ron said, there actually is a good way to what you want. First you need to select the bodies you want to group. You can do this, while holding Shift down in Windows, either in the Browser tree, which can be a little tedious if need to expand multiple components to get to desired bodies. Or you can go to Select > Selection filters, uncheck Select all, then only check Bodies, and from there select the bodies in the model space while holding shift down. Then right click and choose Create selection set. Now when you want to change visibility of these bodies, find that selection set in the Selection set folder in browser tree, choose the Select option, which will select all those bodies in the set, then finally right click and choose Show/hide. And viola!
Another related ability I use quite a bit is Inspect > Section analysis.
Hope the guitar is coming along well 🙂
Jesse