GM-
You've touched on a few topics that I have given a lot of thought to....
Your estimate about the displacement of the Revell model is a pretty decent approximation, but a little high. Having built the 1/72 scale kit, I know it displaced about 5.5 pounds. Cutting the scale in half means the displacement goes down by a factor of 8, which works out to about 11 ounces. (Using the displacement of the original and calculating the value directly will be more accurate, as it avoids the error introduced by estimating a percentage of volume.)
I have also sailed both RC and pond sailers. The issue with scale sailing models is that while the displacement goes down by a cube factor, sail area only goes down by a square of the scale. So this means that any scale model is carrying a lot more sail area per pound of displacement than the full size vessel did. Then there's the factor of winds-- we often sail in what would be full scale hurricanes! The only way to compensate for this is to have a hull form that is much stiffer (lower cg). We do that with deep, non-scale keels with a lead bulb.
You're right about the distribution of heavy items amidships. (But fuel oil is lighter than the water it displaces.) But that is also balanced against the displacement of the hull sections. The finer ends at the bow and stern don't have the bouyancy to support as much weigh as the fuller hull sections amidships. Balancing the distribution of the weight along the length of the hull was especially critical in wooden ships-- to prevent sagging or hogging.
The goal with an RC scale boat is try for realistic looking performance on the water. Neither water nor air (wind) scale down, so you can't scale it linearly. For example, if a ship had a roll period of 20 seconds, a 1/100 scale model will look toylike with a 2 second roll.
Getting weight in a model as low as possible is the key, to increase stability, in terms of roll. But experience shows that fore-and-aft weight distribution is much less critical-- you can only move your batteries and any ballast so much- the rest of the model's weight distribuition is largely controlled by the full scale design.
A ship's turning circle is easier to scale accurately, but no one wants it. I find that many RC boaters have no idea how much sea room ships need to maneuver- they drive their warships like they are speedboats. For example, a FLetcher DD had a tactical diameter of 950 yards at 30 knots. At 1/96 scale, that is a 4 foot model, doing a 30 foot circle! Most skippers want tighter turns than that, so they increase the size of the rudder, the max deflection, or both.
My apologies if I've given too long-winded an answer for what you were asking.. Liek I said this is a topic that interests me. It is the intersection of many things of interest to me: Naval Engineering, my time at sea, full scale ship handling, applied math, rc boats, and plastic scale models!
Bottom line, even a model as small as the Revell 1/144 Flower can be converted to RC and look good and handle well on the water....
-Bill