I finally found a charger I like for LiFePo4 batteries. It's still not cheap but its programmable for individual cell voltages, does cell balancing and can discharge cells. I'm using a generic power supply to run it but you can charge using a lead acid battery, it converts the input voltage to whatever you need to for the cell you're charging/discharging. Max charge rate is 30A so it doesn't take a week to charge your cells when you're top balancing (like the 6A charger I was using did).
https://www.progressiverc.com/products/icharger-x6
It will charge all your RC batteries too. You could use it as DC-DC smart charger to charge your LiFePO4 from your tow vehicle alternator.
Bruce