You can still save. When it says the scene is too complex, that should just mean it's going to save at the "start" of that area. So for example, say you land in an icy region. And you do a bunch of things in this icy region. Then you hit save. It will say it's too complex. So if you restore from that save, it's going to disregard everything you did (on the icy region) and taking you back as if you just landed at that icy region.