I've been waiting for something like this. Any missile that size makes a hell of a lot of noise because the exhaust gasses are supersonic and blast continuous shock waves in their wake.
Look at the amount of water they have to dump on a missile plume during ground based launches to prevent the sonic shock waves from destroying the very vehicle creating them until they reach an altitude and speed that the shock waves dissipate behind the launch vehicle.
A couple days ago an anon was asking for more camera footage in order to triangulate the launch site/area. He had some maps ginned up and had the primary azimuth plotted from the Skunk camera position. I never saw any follow up posts. Even without triangulation we do have his azimuth (though I didn't earmark or save that, dammit).
If any anon's are in that area, why couldn't one start down that azimuth and just question people if they heard anything that night? This thing didn't launch in a vacuum and if it was "heard", even subliminally, 150 miles away then it had to definitely have been audible (if not deafening) at much closer range.