I finally bought the parts I needed to add my extra '12 ama to my '15 Oasis and it seems to work fine. I bolted the crossbars behind the seats as far apart as possible, which is still 1.5" shorter than the distance on the AI. This means that the ama will fold in, but it doesn't feel smooth near the end and probably stresses the hardware a bit.
To keep the ama in the water with the higher deck of the Oasis, I added 12" lengths of 1.5" schedule 40 aluminum pipe to extend the feet of the akas. The first slid on with grease, but the second required some sanding. The OD of the pipe conveniently matches the ID of the bottom of the oversized holes in the ama. Wrapped some rubber flooring material around to make the top snug.
Works great. Taken it through surf for crabbing and salmon fishing.
I forget if there's an easy way to include pictures on this forum. Do they need to be hosted elsewhere? Until I figure it out, the pictures are available at
http://www.norcalkayakanglers.com/index ... ic=86177.0