That helps. I did not realize that even if I supported my upper legs I would also need to support the above the knees too (was kind of thinking that the control would be with the upper legs, not the knees, hence I could let the knee caps go freely up towards the skin on the deck and thus have lower deck compared to if I had a brace on top of them).

I am not sure yet how long I want the cockpit to be - I need to put together a "jig" to see what feels comfortable, I suppose. I've never paddled a boat with a cockpit of less than 28" of length, which due to my 36" inseam still meant I had to sit on the rear deck and sqeeze-in that key-hole cockpit legs-first. Once in, there was plenty of room vertically (12-14" from hull to bottom of coaming, depending on boat), where on the SOF I am tempted to experiment with a tighter fit - looks like 10" internal room at the upper leg and about 12 for the knees is the least I would be comfortable with due to my tight hamstrings (not to mention at least 9-10" for my size 15 feet)...

I like a long cockpit for longer A to B paddling as typically keep my knees in the middle and paddle with plenty of leg action - I am not sure at all if I will be comfortable for extended time (2-3 hours) if I can't do that (stiff back/hamstrings)... May be I need to put a temporary "masik" in my current kayak to see how that feels before I decide.

: The masik position will depend on the size of the coaming you plan to use as
: that is it's primary duty. If the coaming is sized small (round), the
: masik will be well up your thighs and you need a knee brace beam to
: support your legs just above the knee. If the coaming is longer (oval),
: the masik can serve to support both the coaming and your legs. I've done
: this on a couple of boats, since I use a coaming sized the same as a VCP
: ocean cockpit.