So, a very small building project was in order. We decided to recycle an old barn door for the purpose....
After a bit of reinforcing and some slats added for strength and traction, it made a fine ramp.
We put some scraps of plywood along the side so that they won't create a den under the ramp. We don't want them undermining the foundation of the barn, something they are more than capable of doing. The ramp itself is sturdy and firmly anchored to the barn.....I do have some doubts as to how long the plywood will hold up though. If they decided they want to go under it, there is not much short of nuclear weapons (or electric fence) that will stop them.
...and then start looking for ways to either eat it or destroy it, preferably both at once.