Best workflow for building light in a interior/exterior level?

Hello, I’ve been wondering which could be the best workflow if I want to create a detailed interior scene inside a landscape exterior with high amounts of foliage.

I already did my exterior landscape but its taking so long in building light (even in Preview mode) so I’m afraid of thinking how much would it take if I also have a detailed scene with props.

So the questions are :

  • Which is the correct way? Create the interior scene in another level? Inside the same one? I want to see the exterior from the inside.
  • I want to use high Lightmass Settings specially in the interior. I’ll also have some Lightmaps around 2048 in size so it would take days! I don’t really care about not using them in the outside.
  • If it would take less time I’m thinking in watching the landscape just by the window without interacting with it.

Thanks in advance!