...Depending on the amount of leg room you
allow and how much the seat is reclined,
I got about 3 feet difference in passenger
CG...

If there is a 3 ft. shift in cg with passenger mass, I suspect either your
calculations, the mass distribution analysis, or the wing placement is wrong.

Cg shifts are predicated on the overall mass distribution. If a passenger can
shift the cg 3 ft., something is wrong, especially on a two place airplane (I
am assuming this is the airplane that was on the linked website).