I assume you have 2 rod holders on the gunnel, this idea may work with one as well.
Use a piece of exterior 3/4" ply wood 2' wide by 3' in length. Cut the wood in half 24"x18" or so.
Install three stainless hinges on the bottom of the table for a hinge.
Install the Magma table mounts on the bottom of the table near the ends(they fold up for storage).
Cut 2 pieces of wood in with a U channel that accepts the gunnel, maybe 4-6" wide along the gunnel. You likley only need to go a few inches over the gunnel on each side (over rub rail). Install a strong rubber pad on them (I suggest heavy white rubber that is used on electronic rework benches - quite heavy. I use throw these over the gunnel in the NE when lobstering) so they don't scratch the boat or hurt the combing bolsters. Screw the two U channels near the hinges to each side of the table.
To install, you open it up, and simultaneously slide the U channels over the gunnel and guide the mounts into the rod holder mounts and lock the mounts down. The table is held in via the 2 mounts and the two U channels.
The U channels will give a good stable platform abeam and the two rod holder mounts lock it in place fore/aft.
It would fold up fairly neat 24 wide X 18 long by X9 thick. You could make the table smaller if you have storage concerns.
Just a thought...