N.b. the A321 left 'ahead-of-the-wing' emergency exit is in fact a full size boarding door. Same as the other 4, different from the other 3.
Leisure operators don't use containers due to logistics challenges and lack of equipment. Those only makes sens for a specific mission and operation profile which is out of reach for most airlines.
The turn-around times should not be yield critical on a 4500 NM sector proposed. Even if, the most time consuming is the availability of cleaning teams (late arrival, missing supplies and insufficient numbers) which is why the successful ULCC try to get away without them.
On a short (below 2 hrs) sector with a reduced and pay-to-consume catering model this is possible. 9 hrs sector I don't think so, also the cleaning needs to be somewhat deeper than intra-EU experience normally requires.
I mean to say that for the proposed airliner pax, bags and cargo manipulation does not seem to be the limiting element.
Regulatory stick time is (one of them). Whether you can make 7 + 8 hours legs in one day with 3+8 crew, assuming normal complement 2+5. Unfortunately EU has broken that barrier already, US and China not yet
AFAIK.
So expect the newly proposed ship to have a full bunk.