Did you fasten the aluminum strips to the headlight, or was it just a friction fit?
What department/area at Lowe's?
I think it's the hardware department, you'll see they have several types of aluminum and steel rods and stock in a section
The tabs on the headlight have some I'll call it channeling. When you shave the tabs, you can slide the stuff I showed above into the grove. I did at one time have some set screws to hold it in place but didn't use them this last time and it's wedged in there pretty tight.
Once you have those in place, you just screw you top strips on top and then you have the perfect platform for the amp.