Right going to give you a few quick examples of 1p and 3p models made with the two main methods using the Lynx and the Chinook, then going to also give you an example of the landy 1p and 3p models as that should help you too
First of all the Lynx, which is been made in Method "1" as talked about earlier, with making a low poly interior then making the high poly interior afterwards.
3p model first, got everything there you would expect and low rez interior etc, 3p model also made out of 6,035 tris.
Now here is the 1st person model, notice looking from the outside we can see lots of missing faces but once we are sitting in the pilots seat or in the back, we can't see any of that, also notice the higher rez models and mainly textures, but still the tri count is less than the 3p model at only 3,637 tris due to the exterior faces being removed, also the rotor blades, air filters etc all all separate objects and they stay on there 3p models with just how BF2 works, although you need the main rotor anyways since you can see that from inside it hehe:
Now here is the Lynx's 3p textures and if you look hard enough you can see some low rez elements of the interior textures:
And here is the 1p textures, notice how none of the 3p textures are on them:
Although the Lynx actually uses very little of the 3p mesh in its 1p mesh, there are still tiny bits that do use the 3p mesh/textures in it like the things just before the pilot:
Now onto the Chinook since I think we have covered the Lynx now, remember the Chinook was made in method "2" where you make a high poly interior to start off with and then for the 3p model you cut down on your tris, although still keep the UVs and you just give your 3p cockpit a much smaller texture (but essentially the same UVs/texture) than the 1p model.
Starting with the 3p model again, as you can see everything looks normal from the outside and on the inside everything looks all right just low rez (in fact textures could be much lower rez and I think in the full build they are, these files are not 100% upto date

) and the tri count is at 11,635 tris:
Now if we look at the 1p model we can see the interior has a bunch more tris, higher rez textures and the exterior faces are all removed and the tri count is at 4,915 tris:
Now if we look at the 3p textures we will see there are no cockpit textures on them:
We need to open the "3p cockpit texture sheet" in order to see them:
Where for the 1p model, you see the same sheet, just in much higher rez:
The way the Chinook has been modelled above (method "2") I personally wouldn't recommend. It is easier to make the model this way yes but its at the end of the day, performance wise it isn't as good.
Now instead of going into Helicopter cockpits going to take the landy here and show you what that's like since its more relevant to what your doing
So normal 3p model of the Landy at 9,289 tris.
Steering wheel is not very round and all interior textures are really low rez:
And switch to the 1p model and its a very different story, with it also having 4,067 tris.
Now if we look at the 3p textures you can see if you look really hard the interior textures just really low rez, if you can't see them just trust me, they are there:
and switch to the interior textures and we can ee the high rez interior. Also strangely enough for some reason many 3p textures are also on the interior texture. This really shouldn't be this way and it should be using the exterior textures off the 3p model unless some item really needs increased detail for the 1p model which I dont really see much need here other than a few small bits like this bit here right next to the driver:
But ye think you should get the idea here of what you need to do
