Tailgate storage

I used to have three bike lifts in my previous garage due to lack of floor space. The only downside of these is if your load is not centered, one pulley may stay up while the other only goes down. You can create a two line pull if that worries you and put a tie down cleat on the wall. I would put the tailgate in a closed sack/pouch with loop straps and use the hook pulleys that come with the kit.

I also have a fancier Thule Multilift for a car top storage box, but it is overkill for the box or a tailgate.

https://www.thule.com/en-us/us/cargo-carrier/car-top-carrier-accessories/thule-multilift-_-1689689