The Scotty triple mounting bar is pretty popular and you can mix and match using rod holders and the removable fish finder mount. The bar mounts in a single Scotty #241 deck/side mount or one of their flush mounts like the #244 or #344 round flush mount. The new models have three spigots for mounting points.
On the other sie of the coin, is the Rhynobar which is round, and has 2 mounting points and is really secure after you get it mounted right. I have one that I haven't used yet waiting for the right kayak to install it on
On mine, I plan to put a few Scotty mounts on it so I can use a fish finder, and a rod holder and move them around a bit. Below is a good photo of how the Scotty stuff fits a Rhynobar.
With a system like this, you could use rod holders or a Scotty fish finder mount in the #241 mounts giving one ALOT of versatility. If you wanted to use two rod holders for the day, fine. Of you wanted to use your fish finder and one rod holder, you could very easily. You could put three #241 mounts on the Rhynobar without too much crowding also. Just some thoughts to ponder....
PerryC.