The tabletop is roughly the same diameter as the well, and would fit nicely over the top of it. As far as things on the ground that are heavy, what you see on the map is what you get. I will note you have a full tool building and blacksmith at your disposal in the town. Making something crude would be a Survival check, something more substantial would take an appropriate crafting check. I'll give a quite a lot of leeway to be creative here, so long as you can describe what you are doing, and how you are doing it.