Don't add a full espresso dome. Shiny as it is, I'd use a period coffee machine for that. A balancing siphon coffee maker just needs enough heat to get water in the brass tank to boil.
Now this is beautiful! Any idea where to find them? I have about 9 sqft of useable rear deck space, and could incorporate bracketry by utilizing the rag top hardware, with minimal alteration to the carriage.