Thanks for that all. I'm a very experienced sailor but the west coast is a pretty finicky bit of water. I've done it the other way round but not up. As I guessed it's a no no without some sort of autohelm.
I'd be interested to read of any incident with LIFEPO4 batteries being identified as the cause of ANY fire, ashore or afloat, BMS failure or not. LifePo4 batts are VERY hard to make burn (ABYC tried to do it and couldn't) - other Lithium chemistries have no place on a boat IMO.