This I really think you could do in 8k tris quite easily, 9k tris I would say tops since its basic shape is really, pretty basic and a lot of the details can and should be done with a normal map rather than polys. Right now your spending waay too many tris on the tiny little details that add pretty much nothing other than if you get really up close and personal with this.
As for tri counts, 10k tris is really the absolute limit this should be for its 3p lod0 model, but tbh, I think you could make it a lot lower than that without loosing much detail.
If a interior is included in the 3p model that's really about if its going to be seen or not. If you have a rear hatch that opens up or some other way of being able to see the interior, you need a basic, low poly interior as part of the 3p model like the same you would have for a cockpit and passenger area of a helicopter. Best way to do this is to make a really simple one then bake the normals and texture off the 1p model with its textures and normals for the best looking, lowest poly and quickest result (although you will need to leave the baking part out until the 1p model has been made and textured).
3p:
http://i.imgur.com/QUBVSbi.jpg
3p lighting:
http://i.imgur.com/9vpFjs0.jpg
1p:
http://i.imgur.com/2fLHLFC.jpg
But for an APC, a passenger interior etc really shouldn't be part of the 3p model in BF2 since there is no good way of opening up an APC and having players climb in and out, and they just appear out side when they exit as we all know. If you look inside the 3p model of the AAVP7A1 you won't find an interior:
But if you look at its 1p model you can see an interior:
But TBH the AAVP7A1's interior isn't as optimized as it could be, in the respect that the driver and gunner are also loading the passenger interior, and worst of all its textures, which they can't even see. If they where two different lods the driver and gunner wouldn't need to load them, like on the Wessex (although its 1p models use 3p textures since no proper, high detailed 1p models and textures have been made for it) but this is how the AAV should be setup and what you should aim to do:
3p lod0:
1p lod0 (pilots see this):
1p lod1 (passengers see this):
As for the actual 1st person tri count of each 1p LOD, a low as you can possibly make it really with trying to add more detail for the bits that are in the face of the player, so turret should be much more rounded up etc but you can have 1p models with 10k tris without any significant problems, but the important thing is to not waste the tris on things the players can't see/notice.