Can empathise with this, Dylan had a testicular tumour removed, plus one of old spaniels had the same as Rosie. Our furniture all got chipped! I think there are now softer cones you can get, rather than the hard plastic ones, they are still firm, but not so lethal.
The only other thing I could think of is maybe a babygro or surgical coat (they are brilliant), and put some padding in like a nappy?
Sending hugs to poor Rosie.
Lesley and Dylan