I have heard the "midget whites" are close but not the real "midget whites"..However, that is not a big deal as with sop's we deal with a bird that looks like and conforms too and "purebred" does not really count. We do not have pedigrees.
If I wanted midget whites I would start with beltsvilles and RP's. by selective breeding you could get to them in 10-15 generations is my bet.
Also they would be a place to start to get a jump on the number of generations needed. One of the things I like about the RP is there small size. The last time I processed a turkey (RP) and a Chicken (toad) together the RP dressed at 12 pounds the Chicken at over 15.
A silly question probably, but what would breeding in the royal palm do for the Beltsvilles that would make them more like Midget Whites?