Modifying height of Tite-Lok Black Widow rod holder?

I want to add a second Tite-Lok Black Widow rod holder to my boat, but the location need a unit approx. 12" high. Tite-Lok offers a short base but it is way too short at 3". The description of their Ultra and Supreme says they are 18" tall but state "The 18" tube may be cut down to desired height using self tapping screws to tread."

I don't follow what they mean by this after looking at my current 18" Black Widow holder. It is welded at the top and bottom and I see now way to cut down the tube and reassemble using screws. Their phone goes to voicemail each time I call and they have not responded to my email. It would cost too much to have a shop weld the tube back together if I cut 6" out of it.

Maybe I'm being dense and somehow it really will go back together with screws?

I have hitecks on the back of my walleye boat and I just cut them down and had a shop weld them back. Should not cost over 10 fo 15 if you cut them down. Cut off at base and take whatever out and weld back to base.

Some of them have a threaded rod that goes through the center of a round tube. Just cut each and screw back together.

The top of my crossbar does have a threaded hole, and then three threaded screw size holes, but I see no threaded rod or other way to reassemble it.

I'm not familiar with the particular item, but if you post a few pictures on here, I bet some of the many engineers, machinests, mechanics, etc on here can give you a few ideas.

i looked at them online, not sure my suggestion has merit. I see nothing but a 2" diameter tube, that would require cutting off and rewelding, but maybe I'm also missing the obvious!