Agree...That is what I would do now if she is ready mentally... but I wouldn't recommend get totally stacked over the rear leg.1. More stacked over back foot, , not so much flexion in back knee during negative move (basically stand taller), remaining coiled into foot plant
2. Stay more relaxed and stop muscling, I think she does that in her game swing anyway
I think number 1 will help with quite a few issues we are seeing
Since she was and still is to a degree...hip flexor dominate,,,,being totally stacked over rear leg...could be counter productive and would by-pass the chance to use the load as an exercise to build the other muscles/movements that counter that dominate pattern.
Consider working the glute/posterior chain with hip hinge and transverse plane with external hip rotation (hip counter load) building more stability there.
Working these 2 patterns...with a little less leg flexion....may require her to decrease her stance width by a 2-3 inches.
1. Hip Hinge
Bend at the hips...Rear out first..then slight knee bend
2. Rear Hip Load by slight external rotation (rear pelvis on femur).
My instruction would be like this
a. Stabilize the rear ankle by using the toes to grab ground.
b. Screw rear leg into ground..keeping knee inside foot. Taking slack out of rear hip and feeling tension build into the rear hip. Hips will counter rotate just a tad doing this. Want a very stable rear leg and stable rear hip.
c. From there... just working the load as a movement pattern (like Romero below)
This is counter rotating at the hip...and trying to resist full ext. hip rotation or stopping further ext. rotation. This will increase her ability to control/stabilize... the rear hip.... using the muscles she hasn't been using fully.
I also build them up from here... by doing the same load pattern with a hitting pod or balance pad under the rear leg...while trying to keep the rear leg relatively still.
As always...movement patterns 5 times each... then a few swings...back and forth.
Just a suggestion. Good Luck!