I built the kits basically as suggested, but added sides to the flatcar so that it could be used in coal service. The cut levers on the flat car are standard staples, and the trucks are Marsh Creek products ordered from shapeways.
The paint is Americana craft paint: two parts "Deep Burgundy" to one part "Georgia Clay." I tried a number of mixes before settling on this one. The flat was lettered with dry transfers but it was hard to place them accurately on the thin sides, so I bit the bullet and ordered custom decals before lettering the boxcar. Early-20th century railroads that had a "Saint" in their name (M&StL, CMStP&P, etc) tended to place the "T" above the period, so I replicated that practice.
I am 80% done with the road's first caboose, and am also working on converting the Peco N scale turntable to a model of an SR&RL wood turntable. More to come soon...