RE: Best set-up to get comfortable with planing
I haven't fotgotten you. Please be patient and I will give you a thoughtfully crafted answer.
My first guess is that your girlfriend is not yet committing her weight to the rig.
Even on a board a blocky and bulky as the Prodigy, if she steps out to the outboard footstraps and applies and of her weight to her feet, the board is definitely going to react to "weight steering" on the upwind rail and promptly turn into the wind.
Maybe her new "mantra" needs to be to get going a little faster before moving out to the rail, sheet in a little more slowly as she moves back on the board to prevent any sort of "rig steering" and then THINK LIGHT" and make sure virtually all of her weight goes onto the harness and rig and keeps her from putting weight on her feet.
I'll be done with the Trade Show and demos in a few days and hope to have more time to devote to giving good answers here on the forum.
Hope this helps,