The way *I* like to do something like this is:

Create a new model space (you can call it inactive)


Model->Add Model;
then give it a name "Internal Struts" ; Model type "Inactive", hit enter.

You create an 'empty' model space that still has your backdrop images.

Scroll (Shift-M) to the Main Model, select and copy just those parts you want to work with.  Scroll (Shift-M) to your new model "Internal Stuts" space and paste the selected parts therein.

This way you have JUST the parts you're working with, you can create your new parts and adjust as needed.

Once you're finished, copy the new parts back to the Main Model page.

For me, it's "cleaner" than hiding parts in gmax.  This way I have a clean page to work on, without the distraction of other parts.