You probably don't even need to go straight to the battery. A good friend has a cheap 100A Daly BMS and his windless is fine. Remember, the engine should be running when you are anchoring, so the LFP battery only provides the difference between what the load is and what the alternator puts out.
Also, the rating is for continuous current, the BMS will handle more than that for short times. So, if your surge current is still under the BMS rating, you should have plenty of room. I expect that a 200A FET based BMS would handle most windlasses and thrusters without any problems at all.
Put a meter on your windless and thrusters, and find out what they really draws under load.
Another possibility, you can have a relay who's coil is controlled by the BMS. You do not need a special relay output on the BMS to do this, any FET BMS will work. Just connect the coil to the BMS load connection, in series with a switch to serve as a Windless disconnect. Then the common contact of the relay can go directly to the battery. So, you still have BMS protection, but the high load of the windless doesn't go through the BMS.
As I mentioned before, I am a fan of FET BMS's. FETS are more reliable than relays. In fact, the friend mentioned above with the Daly BMS used to have a BMS that used relays , one of his relays failed closed, and his battery melted. I helped him rebuild it, and he is much happier with it. FWIW, we selected the Daly because it was available for 24 hour shipping and he was pressed for time. It isn't my first choice, but no complaints, he has been using it a long time now without any problems.