Vehicle manufacturers know the alternator will only be delivering its full output for short durations, so they cut every corner they can. It is not uncommon for a 160 amp alternator to have a continuous duty cycle of less than 90 amps. Under the extra load imposed by high power mobile applications, the alternator and/or the interconnect wiring may over heat. This is especially true of low content (minimal accessorized) vehicles.
Also, you'll need 60A worth of wire (or whatever your alternator is rated at) to connect from your alternator to your battery. Then there's the issue of trying to combine a start battery with a LiFePo4. I don't combine my start battery with the house battery, the two different batteries are hard to combine and charge correctly since they are at different voltages (12.8V vs 13.5V). So the question isn't can I a charge a LiFePO4 battery directly from the alternator but how long will it work until the alternator burns out?
I attacked this problem by using a Renogy DC to DC charger. Now you're only drawing 20 or 40 amps from your alternator and you also get a LiFePo4 charge controller so you don't have to worry about overcharging your expensive battery. You're also not combining batteries, the Renogy won't back feed the start battery from the house battery.
I didn't want to run huge wires through my truck to charge the battery or risk overheating my alternator so I'm using the 20A model. I've only used it twice so far but each time it's worked as expected. Renogy isn't know for high quality products so YMMV. The Renogy doesn't sense state of charge to turn on, it needs a +12V signal. You could wire it to an accessory that comes on with the key but I wanted to be able to control mine. I have it connected to my running lights so it charges when I turn them on.
I also have a 220W PV array and a Victron MPPT charge controller connected to the battery. I can charge at 35 amps or so when the truck is running and the sun is out. No special wiring is needed, just connect both the controllers to the house battery and it just works.