Don't hide the items in the Main Menu block, but hide the main menu block itself. By doing this, you will be able to link to anything in the main menu from anywhere. For example, on this site, the "Main menu" you see on the left is just an html block. I have the default main menu block hidden and am linking to things created there from several places...I also have some things in the main menu block that I don't link to (like surveys), which allows me to email people links to a survey, but not have it shown on the frontpage for everyone to see.
A little more work, but effective.