Eddie, the chain plates are easy to remove and inspect. There's a few screws holding the molding on that covers the aft 2 plates and they are easy to get at when the molding is removed. The foremost plate might require more work. I took mine out when the boat was gutted. Not sure if you can get at it by just removing the trim plate at the back of the top shelves in the head or not. If not you'll have to remove the cabinet face. That's not difficult unless th ere's a spaghetti bowl of hoses in there. The port side is easy to reach through the wet locker doors. When I took mine off they were pristine. The boat has spent about 2/3 of its life on fresh water.
I have a lot of pictures of the inside when gutted. I had everything out I could get out without destroying it. If you have a need for knowing what's behind something removable I may be able to help.
Lauri, I can give you partial measurements of the ice box. The fore and aft dimension is 23", The athwart ships (is that the right word for perpendicular to fore and aft?) is 25 1/2" at the fore end and 17 3/4" at the aft end. This was taken about 10" above the floor. Because of the sloped side it will be larger further up. Unfortunately I don't have the depth. I can estimate 30+". I can not reach the bottom without standing on a riser. I'm 5'9" tall. If you know the height of the counter top that is close.
Geoff