Not yet...
Still searching the internet for answers.

Any clue as to what genius put the plug right behind the mount?

Edit: Seems to be a common occurrence on many vehicles to locate the freeze plug behind the mounts.

 

Site sponsor Lucky8 has freeze plugs.
I don't know if they sell them individually, but the whole set is around $12.
You can rent a tool at an auto parts store.
Put a jack with a block of wood under the crank pulley for support.
One nut on the bottom of the engine mount, and 2 bolts go into the block. Remove those, jack it up very little and remove the mount.
Clean the freeze plug hole, put the type of rtv sealer made for them in the hole and on the plug(a small amount on both surfaces).
Put the new plug in place and hammer it in with the tool, make sure it goes in straight and flush, put the mount back and you're done.
The only hard part is that it's awkward to get to.
I also wouldn't do it in freezing temperatures, as the rtv needs to cure before running the engine.

 

Get a floor jack and a bit of 2x4 to raise the motor and remove that mount. Then install one of these expanding type plugs. Measure the hole so you know what size to get, or someone here may know.

 

Thank you both.

I contacted Lucky 8. They informed that there are 8 total freeze plugs on this engine. Obviously I'm only going to fix the one but, it's good info to know.

 

Yes, 3 per side, and 2 on the back of the block.