Having tried my hand at axe throwing, I'm wondering if there might be an additional rule promulgated: a nearer Throwing Line for Women. In golf, there's often a 'ladies tee'. That might be appropriate here as well.

Proposed Assumptions & Calculations:
Men's Throwing Line = 20'
Man = 6'-0" tall
Woman = 5'-6" tall
Proportion (5.5/6) = 92%
92% x 20' = 18'-4"
Assumed Handicap for Differentially Distributed
Body Mass = 2'-4"
Women's Throwing Line = 16'

Any other suggestions?