I would also use PL (panel adhesive) in between the 2 layers, screws and offset the joints like someone else said. This will stop the squeaking you'll create with the 2 layers, and make it stronger. Stuff is cheap and comes in a caulking tube. BCD.
These are what I have. Simple, no cords, plugs and hanging chains to deal with. The third pic is old, but now with the white steel on the wall it's brighter. Bcd
I havent had any trouble with the compressors but with mine its always been the fan that quits. I take the motor apart clean it and put a few drops of oil on the shaft. But a month later is ceases up again, tried different oils but same thing. So I changed out the fan motor with a ball bearing...
Have you checked with online diagrams, I haven't been to the site for a while but check out "Logan actuators" I've got drawings for my Logan there, you can still get parts and they might have other drawings also. BCD
If I had them they would be all scraped. If you go through every screw and nail and as many buckets and pails as I can imagine you have to deal with your going to be a long time at it. BCD.
I noticed the seam sealer I used took a long time to dry throughly , it got a skin on it but took a while to get solid. ( weeks) Was it still soft when you sprayed the undercoating over top? BCD.