Nice work! Not enough rivets for my taste (
), although I obviously see your reasoning; still, in my opinion, the main difference between a VSF/ESF and Interwar/Dieselpunk walker would be a combustion engine and a camouflage paintjob, as opposed to steam and brass/navy grey/white schemes.
The first one is really great. The only issue I might have with all the designs is that the feet look a tad bit small. Obviously they are finished, but some "toes" like on the first one might improve it (they look a bit toppling-prone).