Rick, I am having Pic issues. Do you want to discuss via email?

We can - rickk@classicaquasport.com

Got around to measuring up and cutting the console down to fit the new T-Top. Need to grab a couple of sheets of Melamine to use as mold backer to build it back. I cant wait to get a deck built and start mocking stuff up!!

Very good. Now enjoy!

Other than Coosa or similarly priced materials or plywood, what other decking materials work.

I've had good luck with Nida Core (Plascore) using it for deck core, used 5/8" and 3/4" but it has its drawbacks.
Two versions available, with a scrim and without. Just a thin covering on the surface to help attach fiberglass. Get the scrim.
My layup for each side was a light coat of resin onto the scrim, then 1 layer 1708, and 1 layer of woven 12 oz., all wet on wet. Panels are reasonably light & stiff as long as you're not having to span a long distance without supports, 2 foot x 4 foot area was no problem.
The edges are the most work. If you've got an opening for a hatch and need to fill the sides of the honeycomb it takes some time but not a deal breaker. You also can't put a screw into it without prep, filling in the honeycombs, I added Divinicell as a backer where I knew I'd have screws.
It's cheaper than structural foam core.

Do you have access to a fiberglass store? You might look for a small piece of Plascore or other honeycomb composite.  They're very easy to work with and when it's glassed on both sides, it's stiff.
On the bare hatch glass I would grind it down and if the sliding hatch is already stiff (can't twist it), then add some 3 oz CSM (chopped fiberglass) and roll on the resin (I assume poly).  If it's not already stiff then I would add a layer of 1708 CSM side out on top of the CSM added as the first layer. That will stiffen it up.  Then cut your composite (you could use plywood, 1/2 or even 3/8" with glass on both sides is beefy enough. Trowel on thickened resin on the hatch, as Fishhead mentioned, lay in the core and you can wedge a 2x4 up against it to press it into the resin. If you're going to top coat it with a layer of glass then you might want to bevel the edge of whatever core you decide to use - 1708 doesn't like to traverse corners.