It takes winter conditions to cool the battery in any measureable time frame. It's not worth even considering. L2 and L1 charging are easy for the battery to handle. Think of it this way, L1 is ~1kWh, L2 is 6.6kWh. The car can draw near to 90kW under full load, often averages 15-20kW of draw. The motor offers 30kW of regen and DC quick charging offers up to 50kWh. I finally used DC quick charging, twice. After driving from home, charged, drove another hour, charged and drove home. Mostly highway driving ~200km. Charged from ~30% SOC both times and the temp gauge went up one bar, with an ambient temperature of 22C. I drive my Leaf hard, there was zero effort to conserve energy and AC was on full.
L1 and L2 are essentially plug in and forget.
I completely disagree with being concerned about leaving the battery at 100% SOC, for two reasons. The first is this only is a legitimate factor if the car is going to sit unused for a significant period of time. I've left my Leaf at 100% SOC for a week, when I had to leave it and work due to snow. When it was at the body shop for three months, it was left at 70%. The second factor is, I want my car ready to go in an emergency. An uncharged car is almost as useless as a unloaded firearm.