I will try to answer questions on the Mods/improvements. The rails on the wings can be purchased at Lowes or Home Depot, at least that is where we saw them. The rails are attached by screws at the ends and not the bottom. PC stained them to match interior wood.
The table/ottoman has not been used for the third seat yet, but I am sure it will work with the slide-out in, but not sure with it out, might be a stretch.
Moving the light over the sink is an easy task. Take cover off, unscrew light from cabinet and you will find, at least in my unit, plenty of wire to relocate. Drill a new hole where you want to relocate the light, use a wire to fish the existing wire to the new hole. Be sure to turn power off while doing this and keep caps on the wires for extra precaution. Re-attach wires and screw fixture to cabinet in new location. Now there is plenty of room to install a paper towel holder and it is away from the stove.
I forgot to add two photos of important items: Picture #39 is a tissue holder over wife's bed(allergies). Picture #35 is TP holder. Picture #37 is the routing of the heat duct to the kitchen. Picture #38 is the routing of the duct under the platform holding the water tank where it is compressed between the platform and a large wire harness. Picture #33 is hard to see, but I relocated the wire harness (visible at top of picture with red,white and blue wires) relieving the compression restriction on the duct. I removed the wire harness clamp and moved it more inboard allowing full air flow. Picture #34 is a better picture of the clear plastic hose from the valve which allows direct pumping of anti-freeze material in to the fresh water system
On the cup holders, they are available in white and other colors through JR Products (p/n 03-0668) and ITC (p/n 03-1024 81405. On the clothes rod used for towels in the shower, it is listed as Clothes Rod-Collapsible (p/n 03-0964) and available in lengths of 12", 16" and 24". All these items were purchased at a regular RV store.
One other thing is the closet in the rear of the 2551/2552. It is over the outside storage area on the curb side. When it is cold out, you open the closet doors and it is like opening a freezer. There needs to be insulation on the floor of the closet, and the forward and inside walls. I removed the bed board and found it is not possible after construction. Will try to add solid foam insulation in the storage compartment.
Just curious Ron, why do you take off your wedding band at the end of the day. In 46 years mine has only been off when I had open heart surgery and they would not let me leave it on. Ron, you also asked me to let you know if I found a way to insulate in the forward overhead compartments. I did. I bought a new unit and had PC add the insulation during construction. Not a cheep fix.
Bob