[Oblarg]

If I were doing any sort of actuated belly-pan, I'd do two things:

1: Don't actuate the actual belly-pan. As has been mentioned, it's a structurally important piece that you will likely want to mount a lot of important electronic/pneumatic components on. Putting that in close contact to the ground is probably not such a great idea. Instead, have a separate pan on the bottom that is actuated - it doesn't have to be very heavy (plywood should work fine).

2: Don't link it directly with the cylinder(s) you use to actuate it. You're much less-likely to bend a cylinder if you design it such that your cylinder pushes a cam that lowers the plate, rather than just linking the cylinder to the plate.