Notes:

I replaced the heel construction with a heel flap and gusset

24 rows heel flap
heel turn: 19 6 -> 21

decr 2 sts from the heel flap sts in first rd after heel turn

Caution: A stranded heel flap has fewer rows than a slipped stitch heel flap!

First attempt: picked up 13 + 2 sts -> too small
Next attempt: picked up 16 + 3 sts -> better

Next pair of socks: 24 rows heel flap and 21-22 picked up sts

Gusset decreases every 3rd row