Best way to secure garage?

Apologies for the long post.

My current system is a keypad just inside the door from garage to house and we have no problem arming/disarming when we come and go.

I'm looking for the best (convenient) way to secure the garage, two car doors, one outside entry door, two windows.

The issue I want to avoid is coming home through car door and only having seconds (30,60, etc.) to disarm they system.  I don't always immediately go in the house and 3 kids in car seats takes a few minutes.

My initial idea is to add a keypad at the outside entry door, with an entry sensor on it and the windows.  With this setup the car door wouldn't set off the alarm, if I go in the house I can disarm and if I go out the garage entry door I can disarm.  However this leaves the two car doors monitored.

One solution I had was to add a motion sensor, but that doesn't solve the problem.  Thought about using a camera which through settings wouldn't alarm and only provide "post break in evidence".

I have searched for solutions that would integrate the car door open/close signal to arm/disarm the system, but have found none.

The other solution is to use the key fob to disarm before opening the car doors, however this opens us up to human error having to remember and form a habit.  I never use the fob, my wife only uses it as assurance that the system is armed when she leaves.

What are my options/solutions.  Thanks