I also have the comfort seats and coco mats. I had a footrest, but removed it due to possible interference operation the clutch pedal.
There is a "big boy" clutch pedal extension kit the moves the clutch pedal 3/4 of an inch to the left. See Google for details.
I have a Nardi steering wheel. There is a smaller one available, but it would require more effort making turns when stopped, and possible making the steering more sensitive while driving.
My 356 coupe is more comfortable to drive than the Speedster. The latter is definitely not "a built for comfort" item. My legs/knees also splay out while driving. When cruising, the leg room is adequate for me. When doing lots of stop and go driving, you have to pay attention to your foot positions, and give yourself adequate time for clutching and braking.
Give the comfort seats a try. Definitely discuss your questions about seating modifications with Greg. He will tell you what can or cannot be done.
If possible, best to do some more test driving before making any final decisions.
Hope this helps.