IMHO, this "access door on the west side of the garage" is a VERY relevant detail. I haven't personally seen this door, but, will look for it more closely in the future. The most current img shows this door on the rear wall of the garage...is that correct? Or, should it be on the left-wall? There have been plenty of videos showing into the garage when G&C return home, etc. that should show this door if it is on the rear wall.
The same video that shows the K-9's going into the back yard via the fence gate on the left-side of the house should show the "access door" IF it is on the left wall. I'll go look for that one again now.
The reason this is VERY relevant is because it would make it more plausible for Casey to remove the body from the Pontiac and take it directly to the back yard (vs. through the house). IMHO, FWIW, she did this on 6/18 when she borrowed the shovel, dug a shallow hole, then decided it was too much work or would take too much time and risk her being caught by GorC after setting the body in the hole seeing that it wasn't deep enough.