Rigellians! and if you are inventive with the alien gen Denobulans and Coridans! When i get my pack i am going to have at least one vulcan onboard and either a Rigellian or Denobulan.
Denobulans aren't very difficult to generate, actually; I've got one built specifically for late-22nd-century interactions, and the ENT pack gives us a great time-period hull to use, in addition to the uniforms. Until now, he's been stuck in recolored 23rd-century Terran attire, redesigned to appear as close to medical attire as possible.
What do you mean by "character roleplay"? Since the political situation and the story of the missions are set firmly in the year 2409, I don't see how you could do them in-character.
If you mean just a small group of people roleplaying in the 2150s, however, the stats are meaningless, as you don't need to rely on items just for RP.
Also, once the Foundry comes out, you can try to create your own missions in the ENT era and scale them to a difficulty level matching the NX.
The NX is a replica. They are not the ships from 2150. It is a modern ship with modern tech put into a frame that is a copy of the NX class.
Because maybe they want to roleplay it? When you roleplay you can pretend it's not a replica. Just had to say that because you like a few other posters seem to forget it is easy to ignore the current stardate. Pretending is what roleplay is about.
And to others, take your immersion arguments home, Immersion is what roleplayers are trying for, just not yours (LOOK! It says on the box!!!!!, losers).
To the OP, You could play a ship and crew from the past stuck here. Stay with the ship at higher levels. Hopefully you have some friends to help you out on some of the harder missions. A Starter NX at higher levels is about the same as the real NX thrust forward in time.
You can also use the excuse I use. This universe is so f'd up from time-travel, god like beings, and other general crap, that it has become the mix we see now and like any good time travel, dimensional story, we don't even know it's wrong.
My advice get creative. Ignore the "it's set in this time period", immersion people, they are the same people that would buy "Zen and the art of motorcycle maintenance" thinking it would help them fix their bike.
The bridge should have come with the ship. Same as the TOS bridge with the connie should have.