I read from an earlier post that there was parts of the BOT episode, unseen, that the BOP was a stolen Fed ship. If so, I could see it being a Miranda prototype.
Yes, according to the original screenplay
Commander Hansen stated that the design of the BoP must have been a stolen Federation "starship" design (possibly by Romulans pretending to be Vulcans, hence Stiles' remark that there might be Romulan spies aboard the ship - does that mean there were other Vulcans next to Spock serving aboard the Enterprise
Indeed, the Miranda Class ("Starship Reliant") comes into mind and according to the "starship status chart" in "Court-Martial" there was a starship with the registry "1831" which according to the Jefferies Nomenclature would have been a starship of the 18th design, very likely the Miranda Class.
P.S. Can we see these models for graphic illustration / comparison?