Putting an escape artist in an outside pen?

You won't need a pen if you dog proof your yard.

dig a trench out from the fence about 2 ft wide & about 6 to 8 inches deep. lay in some 2 ft chicken wire & attach it to the chain link every foot. Then bury the wire. No more digging out. I did this around my little half acre. & that is the same thing the local Wolf Rescues do their pens & some of their pens are 1/2 to 5 acres.

Put chicken wire under.

Buy a kennel with a floor

lock all your shovels in the garage?

What I would do is not put your dog outside in a pen because if the dog gets out as you are saying then it is better to buy a crate and crate the dog inside.
That is the only way to solve it unless the pen has a solid floor like cement and then they cannot dig.
A cemented pen holds the sides all together and then the dog cannot dig and that would be the only way.
When you put a pen on ground your dog can get out.
All dogs dig and there is no way to stop it.
So try crating your dog inside and the dog will be safe.

electric CATTLE fence?

put the hound in the garage or buy a lrge cage