I have a few temperature probes at my work that have 8" tubes on top of the nuts to tighten similar to this arrangement. I took a socket that fit the hex area and cut it in half. Then added a piece of pipe in-between the two. Kinda made a 12" deep, deep-well socket that would clear the tube that stuck out. Yours would take a large socket but napa will sell large single sockets. A large crows foot may work well too.
