not an easy one..
If you really are worried about deflation you could do a dual system.
Your BA I think is 30 oz.
If you get a Neo Air XLite (72") and a Z Lite (solid foam) and cut this down to torso length (say 51") the combined weight is about 22.5 oz
That will give you more than enough warmth and comfort and a back up if the Neo Air goes flat.
my 3 season mat is a Neo Air (the original) ,never had problems with that but some don't like it ...