I would like to hire an Engineer

Because I have an over extension in my lower back I am not able to ride comfortably in the bucket seats used in new cars. I could ride comfortably in a car with a split-bench seat. My physical therapist has explained to me that most lumbar spines are hyper-extended. For stability people go into an anterior tilt of the pelvis which encourages a forward head and rounded shoulder upper body. Therefore, any seat that exaggerates either the anterior pelvic tilt and/or a lumbar extension via a bucket seat or lumbar support will further aggravate low back, neck, or shoulder pain. After driving short distances in a bucket seat I experience severe stinging in the sacrum and up the spinal column. Since the bucket seat places my hips below my knees, the over extension in my back is aggravated and results in sacroiliac joint gaps on both the right and left sides. Is it possible to design an insert seat which would fit into a bucket seat and result in an ergonomic neutral car seat? I presently own a 2017 Lacrosse Essence.