Have you tried more air pressure? In the photo with the shackles is the drivers side almost vertical? As already mentioned if you have to move the top shackle mounts in the frame I'd go ahead and install sliders, it'll be a much easier job.

Not a chassis tuner so take this with a dump truck load of salt. In the videos I see three things, one it appears just as the drivers front tire comes off the track the rear tire unloads. Two, there is almost no movement in the rear, separation or compression. Three, the rear tire needs more air. I'd add some air to the slicks, slow down the rebound in the front and loosen both the compression and rebound in the rear. In that order.

The above and $1.75 will buy you a cup of coffee in some places.