Piloting and walking around in it can be completely separate and unrelated levels, unless you expect to see combat outside or something the like.
If you are making a better version of elite dangerous because after promising so they never did make ship interiors, maybe lets start with:
“Don’t start from the world’s worse video game ever made”.
Focus on one element at a time.
Make the interior, then craft the exterior to contain the interior you created.
If you go the other way around, you end up with geometry too small for the player to access about 90% of the time.
Also, default 3rd person is the equivalent of 3 fat Americans rolled into one. It cannot even pass inside standard US width doorframes - you may want to consider that when starting. Make stuff larger than the capsule.
Interiors can actually run at 60fps 4k on a 1080 easily with 4k textures on individual objects - BUT - if you plan ahead and stick to a trim sheet set you’ll have much better performance overall (think skyrim style. Look it up, 1 textures covers a whole room set).
In .27 I think simulating physics is mostly broken again.
Might be chaos. Might have been my rig. Might just be the engine incrementally becoming trash.
Either way stay away conceptually from curtains and cloth surfaces so you can actually get to something without cursing every 5m 
Last thing.
If you want players to see whatever who’s driving is doing from windows, you can probably make real windows and leave it at that.
The game will probably have a 2km radius around each ship where other stuff happens and is visible.
It’s space. It’s very easy to render. It’s the absence of nearly everything about 90% of the time.
It has no fog, no light for the most part.
Even if you do something more complex - like that pice of garbage called elite dangerous but done properly - you can easily render the areas outside the 2km range as a localized cube map taken at runtime once upon entering a system
(Because leaving the light of neighboring star systems on would truly cripple any engine).
But again, let’s not pick the world’s worse source as an example at all 
Cube map it. At worse.
And make the windows as holes.
Then a bubble around the interior on which the cubemap is rendered as emissive.
It’ll look far more real than spitting textures on windows.