For boat-tenting I use a sliding gooseneck above the fixed gooseneck as my original boat tent required a higher position than the standard one would allow. I have since made another tent which is a basic Mk1 shape (ridge tent) but retaining the higher boom position that the sliding g-n offers. This gives a lot more space in the boat than a standard Mk1 tent, and makes access to the foredeck via the “front door” less problematic for someone of my height.
The sliding gooseneck stays on the mast all the time now, as I felt that the most likely time to lose it (or even part of it, i.e. the screw) over the side would be when attaching or detaching it. That said, I carry a spare; after all it’s such a small but vital component. It’s a Holt one, I can’t remember the number – there are several subtly different versions, but I did have to modify the mast track/groove slightly with an angle grinder 😮