To gain a bit better access to the top two, you can remove one or both rear crossmember support bolts. Mine came out cleanly after 30+ years, but CA & GA were less salty than other states. That will allow a bit of sag, not dangerous to anything, even the front two motor mounts. You will be able to see the top two. I think. Use a long 1/2" drive extension, or several 3/8" extensions, and crank on them. HF makes some extensions that have a semi-wobble function that allows the socket to sit cocked on the end of the extension. That little bit of wobble allows the socket to fit straight onto the head of the bolt while the extension is at a bit of an angle. If you push the socket on the extension tightly, it will sit straight, so you don't lose that function. The small set as around $10 for half, three eights and quarter inch sized, 9 extensions total.
I used a couple long extensions to reach over the top of the transmission up to the top two/three/four depending.
You may have to use a breaker bar to have enough leverage to break the bolts loose. A length of pipe on a breaker bar will give you even more leverage.
tom