Like JRBMOTO, I just take a rod that is threaded on one end. Insert the non threaded end into the tube end thread it half way. This leaves half of the threads to put a clevis on. The rod can be cut to any length and will support the exposed section. It may be overkill compared to Minn's diagram, but the metal section of the rod will be in past the bulkhead doing it this way.

David