You can certainly sail a Carve 131 with your sails at your weight.
It would seem that for your 150 Lbs./68 kg. body weight you could easily uphaul a
100 liter board, and a 100 liter board would seem much more suitable with a 5.3 m2 rig
in 20+ knots of wind as the surface conditions in 20+ knots would be far too rough for
your body weight on a Carve 131.
With your 7.5 rig, in 12-15 knots, the Carve 131 would be pretty good, but still a bit more
volume than you need to uphaul.
Perhaps you need to examine your uphauling skills a bit and see it you can find ways to
uphaul sucessfully in more sloppy conditions.
The Carve 101 would seem to have plenty of volume for you to slog back to shore and get through
the dead zones in almost no wind.
You would not be planing on either board, so the additional volume will not help much.
Additional width will however get you planing a bit earlier and certainly help with stability