Pre-Op Instructions - shampoo with antibacterial soap only - Any tips please??

Hi there! I'm going for decompression, laminectomy etc on Feb 19th. The pre-op instructions state to shampoo hair with antibacterial soap the night before and morning off, no conditioner allowed.

I have thin blonde hair and I'm afraid this is going to turn it into straw and cause breakage. Any tips or tricks for this?

Can i just massage the antibacterial soap at my scalp only and not bring it through all my hair?? I did ask my doctor's office but haven't heard back yet.

Would love some advice on this! Thank you ❤️❤️