I guess you came right in the end @MostlyBlind, but Smart ANT BMS is quite good for 75 USD and there are other Bluetooth Smart BMS out there for about 50 USD that Will Prowse has recommended (check his youtube channel).
Ahoy. This is, by the by, what I ended up doing. Just simpler.
Yep, from a perspective of being prepared for anything, I like this option, too.
The only issue is that, with LiFePO4, you'll want to make sure that you don't have one battery sitting stored anywhere other than at the recommended...