I think that you don't need to minimize any application, but only execute Show ("NAVI") will bring back Primo and hide other running application behind, which is the intent.
In my end, I started modding my v3.3 MOD and have implemented the auto-timer to launch Primo, if this option was selected from the Custom Settings menu.
I have carver's hack for the nag message so whenever I start my AVIC, it automatically gets into the map screen, and the 15-second visual countdown timer starts. You will be able to press the timer anytime to stop it, and change the setting if wish. A longclick will launch Primo without waiting for the end of the 15s countdown.
My only problem now is that once I launch MainMenu from Primo, I have no easy mean to go back to Primo. Your hack with the AEKMap.exe has only one thing working: Menu button. The reste is not working for me.
But because I have carver's hack so I have an option: the only way that I've found is to go into the System Settings, open Explorer or Show Taskbar, then click on the "NAVI" label on the bottom to bring back Primo; or use scripts or shortcuts from the "Start Menu" when launching Primo from my Mod v3.3. Works fine but not user-friendly.
Unzip the attached file in your iGo folder and overwrite all your existing modified .UI files. Go to Custom Settings to select Primo as the "Start Nav App" (still ongoing and it has to be renamed later though).