If they removed it, you should see two off-set screw holes in your chassis just aft of that leaf spring. At the very least, you'll want to check to ensure those were properly sealed up, because otherwise rust might begin to penetrate that area of the chassis. Or perhaps that's where you'd want to attach a new device as holes are conveniently present.
See this pic from the blog post? See how only two of the four plate holes have sealant residue on them? That's what I mean by off-set. If your van was put together the same way ours was, you should see one hole above the other on two different chassis appurtenances, about this distance apart. The other two holes in the metal plate were unused by Airstream.
I did much of this project (LB_3 did the bench fab portions) and I remember this clearly. For all the general sloppy crap that Airstream did, they were VERY careful about sealing up any chassis penetration that they made.