But if we add another stall to the replica of the Wiscasset roundhouse, it won't look like the original. If it's built with the extended center stall (as was done to accommodate no. 6), there should be room for the two internal combustion locos and no. 10 in that stall.
A small wooden garage off the turntable with a track into it could house the railcar. (Maybe a smaller version of the Albion engine shed?) It should have a door on the back, too, so the Model AA truck can be parked in there, too. Nos. 51 and 52 could be sheltered in the machine shop building, which is heated, unless, of course, one of the steam engines needs to be in there for some reason.