Jon, unless you are very confident, a BKG like this is hard to blend, but not impossible, therefore I would stick to the OP for that, but move the set up for next time. Personally I would have fired a few frames off to start with and then look for issues like the lighter patch, then address them accordingly, this is why to me, if there are issues at the end stage then that simple comes down to planning and you know that
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Not wishing to add to the RP's, but I would like to have seen the BT as you normally process your images, without NIK, I think you would have done/had a better result.