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 45 DS for sale in Italy
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.