Is it possible to replace my turnbuckles on the backstays without taking the rig off? Or would I need to support it somehow?

Jeanneau Sun Odyssey 42. 2 for sale in Montenegro
Is it possible to replace my turnbuckles on the backstays without taking the rig off? Or would I need to support it somehow?
Use a halyard, I’ve changed out chainplates, stays and turnbuckles this way.