We use the summer kitchen option quite a lot. Having the items you need to cook with or handle food right at hand, is always a problem. There is a good sized cabinet under the sink but things can get quite unorganized without a shelf to keep things on. The difficult part about hanging a shelf in the cabinet is the lack of a partition on the icemaker side of the cabinet. I didn't want to make the shelf a permanent fixture, in case maintenance of the icemaker or sink where necessary. My solution was to build a small free standing shelf support, to support the shelf, that is held in place by the shelf itself. What I have is a two piece unit that goes in or out in seconds, without any tools. The support is positioned against the icemaker. Then the shelf is inserted diagonally with the left side tilted up, and then lowered onto the shelf rest. The shelf then has the support pinned against the icemaker and everything is very solid. Of course nothing is square on a boat and everything requires careful fitting, but the end result is well worth the effort.
A two inch high fiddle will keepthing from rolling off the shelf and this should help to keep the compartment more organized. Plenty of room for BBQ utensils, a roll of aluminum foil, maybe a platter or whatever.
I still have room under the shelf for my single burner Coleman propane stove, we use for light cooking chores when we do not want to run the genset.