One thing I noticed is that the tops of the sides of plastic frames is just a tad wider than wooden frames. This requires wiggling, pushing, and muttering under my breath to get them in the bottom frame holders. I have ordered a few medium wooden frames to see if they fit any better. I may end up grinding/sanding the sides of the plastic frames a little to make them fit better in the extractor.
Anyways, I had an old pallet laying around in the yard and we mounted the extractor to that to give it a more stable base (plus now I could move it on a forklift if I had one!). We put 2X4s underneath the top pallet wood to strengthen the setup. Here's what it looks like: