I think I might have a solution to the clothing dilemma.
An idea could be for a job to be to add a new profession called "Tailor" which would allow one to get a Dwarf's or other character's dimensions (who is "designated for measurement") and the better the skill of the tailor, the quicker a fit will be made. From there, you can create a clothing/armor but rather than setting it by size, you set it by Dwarf (and you have the option to hide Dwarfs you don't want to make clothing for beforehand...e.g. that Champion who already has full plate doesn't need more). Clothing types would have a spectrum of low-high fitting, and the closer the clothing type's median is to the Dwarf's dimensions, the better the fit and the snugger the Dwarf (or other creature) feels.