I initially used 1x2 wood and luan to build a test belly pan before I moved on to my current choice of materials. I wanted to learn what was going to be my best method to approach my goals fer my belly pan. One of them was fer minimal fasteners to be removed fer access. Another was adjustability...I can raise or lower the belly pan with some PVC pipe and longer/shorter bolts.
I would say give some thoughts to some "test" materials before you move on to sheets of aluminum. You don't want to find out yer design wasn't optimal fer yer material choice...
