[whpalmer4]

Take your existing perspective, select all of the projects under the Library in the sidebar (but not the Library itself), then cmd-click in the sidebar on the projects you don't want included to deselect them, save as a new perspective...

Note that if a project you don't want is in a folder, you have to deselect the folder after deselecting the project or it will still include the project. If you can put those projects you don't want in their own folder, that makes the job a bit easier, as you can collapse the folder and deselect it.