Hey Ken,
Boy you really have the bug, eh? There are a pile of koi lovers that have above ground ponds. I know a koi collector that doesn't even have a pond! He has a pile of these above ground koi tanks. That's just crazy, don't you think!
You could always get one of those collapsible blue circular koi tanks you see at the big koi shows. They don't cost too much and you can QT fish in your pond as needed, or rear your baby koi each year. When done you collapse the tank, roll it up and put it in the rafters in your garage.
If fact, just like the one we used to house your koi when we rebuilt your pond.
But it sounds to me you are looking for something a bit more permanent. Am I right?
PD