Could not find a decent (hard) barrier that would fit w/ a small footprint and easy to remove.
Have 40 lb Golden so needed just the middle (rear) section closed. Removed middle head rest day one anyway, so used threaded 5/16 rods; nuts; wood grained broom stick.(I should paint the metal portions black). Drop seat for 5 second insert/remove. My wife said the inevitable bite marks on the wood will give it character ?!