Have you considered how much all this added weight will affect your gas mileage on your road trip?
Kidding, but seriously as others have stated IMO you are going overboard. Preparing for the worst is having your gun and a reload with you. If you get stopped with several handguns in the vehicle traveling as far as you are it is MY opinion you are creating a bad situation for yourself.
I UNDERSTAND THERE MAY VERY WELL BE NO LAW AGAINST TAKING YOUR ENTIRE GUN SAFE WITH YOU ON A ROADTRIP. But if you get stopped for anything, you are going to have a million and one questions about why you've got so many guns with you, and why this, and why that...etc. Saying "Because I am legally allowed" is going to be a terrible answer to the repeated questions.
I think you'd be equally as prepared for anything short of civil war with your gun and a spare mag loaded. Bringing a second gun for her which she is not legally able to carry seems slightly ridiculous. Anytime she'd have access to it in the glove compartment, you will be sitting right beside her with your gun. Your hypothetical situation teeters on unfathomable.