My lfp batteries are in the front compartment of the 5th wheel with no heating pads on them. The compartment has had foam insulation added on the walls where possible and did tap into the end of the heat duct in the compartment but it doesn't add awhole lot. With nighttime lows in below freezing, early morning till 9:30 outside temps 25f, daytime getting to low 40s and the cells will stay at roughly 42f and compartment 47f. Still using the batteries like any other day.
Now when the temp hits 10f outside with 25f as the highs, that's when I have to throw my little electric heater in the compartment for an hour to blast the chill out of there. The cells will start to slowly creep towards 32f. The batteries sit on a 1/2" thick rubber mat but the sits on the metal floor of the compartment which work like a large heat sink sucking all warm from the cells at those temps.