Pretty sure the car seat in the middle is not legal anyway due to all of the "latch" requirements. I have a big 5 year old as well and rear doors stay on for the road. He is in a booster and seat belted in. My soon to be 3 year old is going to the same set up soon as he is a monster and does not fit in a car seat anymore. I'm looking into 4 point harnesses for the trails. I have a full cage and harness bars. At that point I'll feel comfortable without the doors.
2010 JKU. 3.5 RK Flex, 37" Nitto Trail Grappler MT, Method 105's. Poly Drag link, Fusion 4x4 Tie Rod, DIY Hydro Assist, Ultimate Dana 44 Front, Rubi 44 Rear. Ten Factory Chromoly Axles, EVO RockStar Skids 5.13's, VKS Shorty V2 with Warn HS9500i, EVO rear D-ring mounts, VKS Prerunner Sliders, Synergy Cage