Boy do I know what you mean!

I have buried cheap wire fencing in many spots in my yard. Wherever they dig, I put a layer of fencing and cover it with about 6 inches of dirt. Eventually, they give up digging there.

And start somewhere else.

So my yard has lots of fencing no one can see. The grass grows through the fencing and hides it, but the dogs can't dig there.

With dogs that big, I'd suggest laying a 4 foot high roll of heavy wire fencing all along the foundation and covering it with dirt. They will dog, but since they are standing on the fence, won't get very deep. Hopefully they will get tired of not being able to dig and leave it alone.

Then you just have to worry about where they'll try next.

Good luck!

Mary