Object is too much complex and uvs are too small. Quality problem!

hi!

I have a complex 3D unique model. Just one part. This model have outside and inside areas.
Three material, intern, externel and one more for expecific regions.
The problem is because I have one single object with so many uvs, each uv is too small and the quality for example to bake in Substance is terrible.
I want to use this object in an Unity project.

What is the best wotkflow here? Maybe to use udim? But and performance?
I can’t separate the itens because are a single object.

I’d chop it up into 1 model per area and maybe 1 per area for props. Then use 1 material for each model.
You can also have 1 fbx with multiple meshes, each with their own material.
Unless you go overboard with draw calls, it should be fine