Paul, love the pictures. What zone are you? Why I ask, is wondering if the hostas make it thru the winter in containers. Difficult to know when we can't see zones. I know zone numbers don't mean everything, but at least gives an idea so we know if questions are appropriate or not.
Some say zone 5A..Some ZoneB..Depends on the winter. Last year was a hard one here. I have a few hosta in heavy concrete urns and they come through fine. A friend here has many in containers. Some years no problem, Last winter he lost several. Correct moisture could be the problem. This Blue Mouse Ears of his has been in this pot for several years.
So, it sounds like what you are saying is that the heavier, the thicker the walls of the container, the better chance they have of making it thru the winter.
My only other option would be to sink the container in the flower beds for the winter. But, if they are smaller containers, that may not do it either since the ground freezes several inches. Altho, the ones in the ground don't have that deep of roots I don't believe.
Most of mine are minis. Dwarfs. In the ground they do just fine.