Guillotine (https://en.wikipedia.org/wiki/Guillotine)

Agree with JJ. (but not with his spell-checker) Use a hoist to lift by the handles, but only far enough to put a couple of blocks under the lid. Then run a strap all the way around the trailer top so when you are raising it and working under it, you aren't relying solely on the handles and their attachment points.

Also, since it is now attached to the roof of your shop, and is at a serious angle, make sure to block the wheels, set the brake and use some method of securing the strap so it cannot try to slide off the end of the trailer top.