@o_lampe I do a lot of my long prints without heat on a Bambulab cool plate - mainly to allow for long overnight or out of the house pauses. Bed adhesion for PLA is actually so good I can't use it for small fragile things.
I'm going to make mine heated though from the outset - and just use the standard SOVOL square build plate - perhaps with the corners chopped off if it won't quite rotate.
I notice now on relooking at the video that he has a very wide brim around the chimney - and some of his other prints look ok - so I wonder if the artifscts you noticed are due to wobble because of the very thing chimney.
When printing the sails of my very tall Sea Cloud model (see youtube) I had to add braces between the sails at a few heights to stop the wobble.
You are right about that filament hiding print quality defects - I was actually thinking of purchasing 3 rolls of it for my printer for when I get on to some big parallel prints - as I thought it might hide the joints a bit.
Re printing in the centre - I think it is possible - but just extremely slow. I got the impression that the non planer solution demonstrated is pretty slow - even for the outer parts.