I have the mtx dx trunk/pannier setup. It has the Quick Trac system and am not sure why you would not want it. But, my work provided me with a Dell D600, I saw one spec that said 12.4 inches and another that said 14.6, so you can look up the spec and hopefully you know more about them than I do. The laptop fits in the pannier with a pair of jeans/slacks wraped around it for protection. It is a snug fit but it goes in fine.

I am sure if you used the velcro straps with the tie down cords on the bottom of the pannier you would not have any problems. As stated above it looks like you could remove the Quick Trac without much effort. Again, WHY???