If you could rent it, then maybe she'd be willing to try it if it wasn't an irrevocable decision. ie, rent your current house, live in the house hack, don't like it?

Revocable trust are great for privacy but usually don’t provide any asset protection by themselves.Do I understand correctly irrevocable trusts do not provide huge assets protection either?

If any of these are the case it is not really an issue as long as everything is properly recorded and irrevocable.

I would contact a lawyer, maybe a friend who would look over the documents to ensure you have everything in order.If you are doing things for estate reasons and attempting to get this asset out of your estate and do not properly file all the correct paper work or check the wrong box to make it a revocable vs. irrevocable trust, then it will stay in your estate vs. being outside of your estate.Joe

But that is mainly because I believe an irrevocable trust should be independent.

If the trust is irrevocable the gain may or may not be taxable, depending on how the trust is drafted.

I'll put the building in an LLC, and the home in a family irrevocable trust with me and spouse in control?

An irrevocable trust will, but then you loose control and benefit of the asset, because technically, it's not your asset anymore.

Unfortunately, there is no additional step-up to FMV in 2015.I am making several assumptions here, including that the trust was "revocable" during your father's lifetime but became "irrevocable" at his death, and that after he died, the property was “includable in his gross estate”. 

Some businesses will be irrevocably changed because of this situation and it will require some getting used to.