"Car seat" hacks? Unique question

[tallman23]

First time on the forums -- looking for some insights. I have a 2014 Murano SV. I'm 7' tall, wife is 6'2'. We fit in our car and don't want to get rid of it.

We're expecting twins.

Infant car seats take up a ton of space in the rear seat. Safety rules state there needs to be a two inch gap between the front seat backs and the car seat -- meaning we have to scoot the seats forward and the seat back upright -- consequently, we don't fit.

Goals:
1. Everyone rides safely (i.e. my knees aren't smashed into the dash or head pressed into the roof liner)
2. Gain anywhere from 2-5 inches of additional "horizontal" space on the rear seat (i.e. getting the car seat to sit further back -- toward the vehicle rear -- on the rear seat)

Thoughts:
1. Remove the rear seat back -- allows the car seats to still hook on the LATCH anchors but removes the thick seat back cushion thereby allowing the car seat to sit further back on the seat. Is it possible to just remove the back?
1a. Would removing the seat back take away energy absorption during a crash?
2. Any other ideas?

Non-negotiables:
1. Don't want to buy a new car
2. Don't want different car seats (they are the number 1 rated safety seats on the market)