Some of the folks over on the MarxTrains group offered their opinion regarding the tender I mated to the Commodore Vanderbilt, i.e. it's the wrong one. The "cigar-band" version I have is from the 1950-1952 time-period, and it was made for use with the Marx wind-ups of the time. It had plastic wheels on it, which I swapped out for tin. Plastic wheels are one of the indicators of whether a car was made for an electric or clockwork version, with plastic used extensively for the mechanicals (probably as a way of reducing weight). No worries as I still think it looks good, but wanted to see if I had a better alternative.
So I went hunting for my box of orphaned tenders (I had recently pulled it out looking for a candidate to use with the Lionel 1664E that's languishing on the workbench). I recalled seeing three or four Marx tenders in there and thought maybe a more correct one could be found. I lucked out, as a nice prewar NYC version was in there:
After reviewing a number of photos of the prewar version of the CV, this appears to be the correct tender. I know there aren't any hard and fast rules for Marx tender assignments, but this one looked like a high-percentage shot at being correct. It has the prewar features of tin wheels, a simple black frame, and fixed-swivel tab-n-slot couplers (as opposed to the postwar sliding version). For now, I'm going with it.