The drag on the mooring is not reallya function of displacement (it is not holding the boat up, but of wind force, current and surge.
You will find a useful source at
Anchors Principle & Performance
where he discusses this,
anchors, scope, and bottom type.
For your boat with a windage of less than 7 sq m the force at 80 knots would be roughly but conservatively 525 kg or 1160 lb well within the safety range as he has built in a 2x.
Linear Mode
