Is this the chest hidden in an alcove in a northern wall, so it looks like it is almost part of the wall? I tried similar things to what you did, with pretty much the same results.
If you use a summoning doll, it should appear away from you, and not get stuck in the rock. You can then select the doll as leader and use it to enter the BF and then exit, getting your characters out. I don't know if your teleporter stone will then be visible and reachable, but it can't hurt to try.
If you reload, you may be able to collect a few crates (etc) and use the
armory trick in act 1 procedure to force a summoning doll to appear close enough to the chest to be able to open it (summoning dolls can not open trapped containers, but IIRC that shouldn't be an issue here).