On my Bundutec Odyssey, the standard jack plates provided just enough clearance to remove the camper. I checked in with Rory (former owner of Northstar) and he suggested extension plates but recommended not stacking them. Placing the jacks that far out from the camper itself places a lot of strain on the jack mounting plates. It makes sense if you think about it given the weight of the camper and the jacks now being that far from the mounts.
Bundutec Campers, like Northstar are wood framed so you might want to check with Northstar as well to see what they think just to make sure.
