Only thoughts, but the tank could probably be sourced from the scrap yard. Stuff like flanged pipe, cut open an old O2 cylinder, etc. With a perfect vacuum, which may not happen, the maximum force pushing in on the vessel would only be one atmosphere. It could collapse, but wouldn't burst outward as if it were pressurized. I'm familiar with things like this. You only really need to tap one little hole for a vacuum hook up. A ball valve will shut it off so the pump doesn't have to run constantly, and a tee off of it for a vacuum gauge is a good idea. With a little familiarizing, it could be a good time saver with likely little worry for the wood. Only thoughts.