Join Date: Dec 2012
Location: Northern California
You should be able to plane the wood down to 1/8" if you use a bed sled in your planer clamped down so that the bed rollers won't be distorting your thin pieces.
If your going to be gluing a thin layer on the plywood top, I would also glue a layer on the bottom to even out the stresses.
In the future you can bandsaw a 3/16" slice, rejoin the face and then repeat for as many layers as you need. Then use the bed roll on your planer to plane all of the slices down to 1/8".
I wouldn't thin the glue, Titebond III will allow you enough time to coat each face if the temperature and humidity are favorable.