Hi Marc, you don't need to be able to bottom out a bolt to remove them, just needs to be thought about differently.
Here's a doodle I did for another member. Get a bolt with the same thread as the post receiver and a nut, a flat bit of wood with a hole through it, some blocks and probably something to protect the body. Arrange like the diagram with the bolt screwed into the receiver. Holding the the bolt still with a spanner and 'tighten' the nut. It will push down on the wood/blocks and exert a pulling force on the post receiver. Just be sure to spread the load and put a rag or something on the body to avoid dinging it.
https://i.imgur.com/fzbwz1Dl.jpg