I like bits of both #1 and #3. #1 tube design contrasts with the square/boxyness of the XJ body (seen pics of Jimmy's XJ with JBitz tube rear bar/carrier which is good regardless).
I have had many a thought how SHS 50x50mm or bigger would look in the same way...for something different as havent seen anyone with one, + match rockrails (mine anyway) and may be easier, unless you have a pipe bender in the shed for doing yr corners on tube.
Also, putting sheet metal onto tube to fab bar would be more fiddly than just going straight out and buying silo section to suit needs, & working with that (that's if you're to go along the lines of #3).
My 3cents worth...