For downwind sailing in gusts, go 'down' in the gusts and 'up' in the slows .... and the most important is to KEEP THE BOAT DIRECTLY **UNDER** THE MAST; dont head up or you ARE going to heel over quite a bit. Since this is a relatively lightweight boat bearing off and going down will result in the boat starting to come on a plane .... "Nantucket Sleighride" so be prepared for some 'bodaceous' boat speed.
Pulling the drop-keel up will aid in the boat's ability to 'automatically' skid-off to a more 'downwind' attitude/direction. If the board/keel is all the way down you have increased risk of 'tripping over the keel' and then going into a 'broach'; if the board/keel is 'up' or partway 'up' you will instead 'skid' a bit instead of grossly heeling over.
I don't have much swing-keel experience (tho that may change soon) but raising the keel when you're already feeling overpowered seems ... hair-raising to say the least
Tho what you're saying makes sense if the hull really wants to get up on the plane and the keel drag is causing trouble.
On reflection, in this situation I would ease the vang to allow the top of the sail to twist off and dump air to keep the center of effort low and reduce heeling/broaching moment...