Well, in the 19th century they probably first indulged in absinthe before tackling the construction board, and maybe they got acquainted with Fitz Hugh Ludlow, so grass may have been en vogue also. That may have led to the assumption that a slanted boiler would give more steam per sqft. of flue surface.
Jose, yes...r/c would permit building a pole road loco which would run on real peeled logs! I have thought about an old Class A Climax pole loco but then would I be building this just to prove it could be done (it certainly can) or do I want to work on the layout I have now (even with a foray into bull-dozing)...?
During WWII, when there was a coal shortage in Switzerland, but electrical power abounded of course, two switchers were equipped with a transformer that had a secondary ouput of 20V, and two electric cookers on the running boards. The current was 12000A, so there were 480kVA = 620hp available. The locos were operated that way until 1951, when the coal situation returned to normal, and lasted in regular SBB service until 1963.