I'm on mission 30 and I have a question about forward operating bases. I want to concentrate on the primary missions first, but it is almost mandatory to create a FOB, when I go online. My question is, Can I create a forward operating base and play offline without getting invaded? I don't want to pay attention to that for a while.
No you can not, unfortunately.
It has been confirmed on numerous occasions that you can get invaded even though you are not online.