I've cut access holes in several places in the bottom corro. I even cut some proactively so that I could inspect or access things like the emergency slide lead screw. On each of those I cut the panel along 3 sides, and simply folded the 4th side for access. Then zip tied along the 3 sides to close.
Not sure if you think you need to fully weatherproof afterward. I didn't. If you do, the belly tape works well, and combined with the zip ties it would stay in place even if the adhesive let go. Even better might be an overlay patch.