LTNman, some of the issues you mention are relatively easy to solve. Only hand luggage allowed that fits under the seat in front on no use of overhead lockers apart from the people at ‘exit’ seats.
Board the airplane from the middle to the front/back and nobody (in theory) has to walk past an occupied row.
Earlier in the thread you said yourself that LLA would have done really well if pax number hit 12 million in 2021 so as a result the queuing at Immigration will be a lot less.