Rocketship Empires 1936 is a campaign setting for a pulp - space opera. It is meant to be used with your favorite table top roleplaying game system. Admittedly some games will support the Rocketship Empires setting with less fuss than others. In particular, games written for the science fiction genre which already include a starship combat system and a means for handling psionics and alien technology will require less work on the part of the game director and players.
With that in mind, everything presented in the Rocketship Empires books is meant for use in a table top roleplaying game and not in a war game. This is to say that the ideas presented for starship construction are merely an aid for directors whose table top rules do not include a starship combat and starship building system which can be easily tweaked into the WWII pulp style starfighters and ships featured in RE.
If your rules already include a starship combat system and ship construction guide, simply review what is presented here and dump the unnecessary structure so you can convert the ships into the system you intend to use.
The bottom line is that in a roleplaying game the structure should serve the fun of the game and not restrict it. When I create starships (like those featured here) I start with the ship construction guide in the back of the core book and then I go wild, writing in broad strokes to achieve the ship I wish to create. I usually base the ships on a historical craft but not always. I do not allow myself to be hemmed in by the location requirements or basic concepts and neither should you.