Beyond a few years of boating I have a few decades of what I call motoring experience in limited suspension travel vintage sportscars (lotus/allard) and motorcycles. Posterior comfort and spine compression from"factory" seat design and materials compelled me to start redesigning my own seats. Whatever factory seat you buy, and I haven't experienced the premium/expensive, plus $1000 versions can generally be tailored to you by choosing amoung the various foam density, and basic foam chemistry. For example, latex foam, or gel pads (found in 18X18X2) sizes wherever medical suppy stores have stuff for people that are compelled to sit all day. Closed cell foam for exterior chairs ( sleeping pads at camping stores) can be cut/glued/shaped and recovered with the original leather/cloth . Another choice to big buck chairs is the adaption of premium car seats from the junkers, I prefer the sportscar seats like corvette/M3 BMWs available for a few hundred in matching pairs, the sportscar seats have a less thick design than the touring car seats, all are adjustable have lumbar support-some are heated. Like paravane rig placement at 28% forward of stern based on Waterline--a helm seat in rough water conditions is best at the 50% position for hobbyhorsing so your body does not rise and fall for hour/days but pivots.