OverRun, of course it won´t be feasible to copy everyting from the A320 NEO. Looking at position the Plus inbetween. A more fundamental choice would be to make it an A321 minus or A320 Plus.
Using wing and OEW-MTOW of the A321 would give it high payload/range but would compromise fuel burn on far most flights. 80-90% NB flights are under 1500NM anyway so I opted for the lighter A320 Plus. Emergency exits of the A321 were retained , I couldn´t find another solution..
A321 has wing adjustments such as double slotted Fowler flaps that could be considered.
JetPhotos.Net Photo » G-DHJH (CN: 1238) Thomas Cook Airlines Airbus A321-211 by Phil Woods
I guess passenger loading - unloading shouldn´t be slower then e.g. A321, 737-900 or 757-200/300.