My Liver and White female Brittany. "Lady" from over 50 years ago. She was adept at waterfowl as she was upland birds. We didn't have dog vests in the 1960s so I kept several towels in the blind with me and dried her off well after each retrieve. She sat at my side out of the wind and cold in the blind.
Cappy ... At my side for thirteen years, in my heart forever.
Go with the neoprene vest and if she still is cold when getting out of the water, take along a Heater Buddy for the blind. I have two GSP with no body fat. They don't have a problem with the retrieval but the boat ride home is another story. We have to wrap them in towels and get them out of the wind. Even getting chilled on the boat rides they still love to load up and go duck hunting.