Brian-
Now that you are 'signed in' with a profile - notice your username appears in blue now - you can upload pictures from your computer directly to the server at kayakforum by using the 'Choose file' button at the top of the reply window.
Try to resize your pictures with your photo software or at an online site (something 800-1000 pixels wide will be enough) so the file size won't be too large.

Now that I have decided to forgo the glassing option, can anyone provide advice on marine paint?

Since you won't be leaving the boat in the water (at a mooring or slip), I think you can get away with any exterior-rated gloss or semigloss enamel. People report using Rustoleum paint on skinboats with success, so that should work on plywood just fine.
Or you could go with any 'Topsides' marine paint from Interlux or Pettit or....
I wouldn't bother with any 2-part paint systems for your application -not needed and pricey.

I am not so sure about the integrity of the hatch covers, as the don't always stay in place when the boat is tipped.

Well, you want to get that fixed! Getting a compartment full of water is something to be avoided. Are they plywood hatches? Are there straps or shock cords that are supposed to hold the covers on?
After you get the hatch covers secure, you could think about putting bubble wrap/pool noodles/flotation bags/dry bags full of air in the compartments as a backup.