Without trust or LLC leaving a restricted item home with a spouse you would technically be committing a felony because your restricted item is in their possession. Something other than by passing a signature or finger printing to consider.
Not as long as it's locked up and you are the only one with the key/combination. My brother stored his machine guns with me for an extended period when his job took him to California. They were locked in cases with copies of the paperwork taped to the outside of the case and they were stored in a closet at my house. Just don't leave them lying around unsecured and unattended....ever.
The other good reason to have a trust is that it will provide a legal way to deal with your NFA items without a lot of confusion or possible violations by your family/heirs if you should die suddenly.
That alone is a very good reason to use a trust.
The thing about LLCs is that the LLC has to be kept "legal" and fully compliant with the LLC laws of the state, which usually involves filing an annual report with the state. If you forget to do this and your LLC is decertified by the state because you didn't keep up the paperwork properly, the NFA items, which are the property of the LLC, become CONTRABAND because they are "ownerless." LLCs are great if you are actually in business and do all the required reporting to keep the business in compliance with the laws of the state, but for an individual a trust is much better because it sets forth the chain of custody for the items up front, and you never need to renew it, make annual reports or anything else. Once it's done, it's done. But, you can add or subtract people from the list of trustees whenever you like and you are NOT presently required to report these changes to the BATFE, you just have to have them sign and notarize a form consenting to becoming a Trustee.
That may change with the new proposed rules, but so far it's easy. Make your spouse a Trustee just in case you forget and leave the item out sometime, then she can deal with it legally.