As I identified in the “Using air conditioning to reduce battery pack temperature” thread, the steady state battery temperature rise is 2.67 degrees F per kW: (127-87)/15. So if you are traveling at 60 mph (consuming 14 kW) and you don’t want to charge at less than 14 kW then your power flow (in and out) would be a continuous 14 kW. At this continuous power rate your battery is going to rise about 37 (14x2.67) degrees F above ambient.
As I identified in the “2018 charging speed compared to battery temp gauge” thread, the maximum temperature that the battery can charge at 14 kW is 123 degrees F. So the maximum temperature where you can maintain 60 mph and charge at 14 kW all day long is 86 (123-37) degrees F. And the maximum temperature where you can maintain 70 mph (20 kW) and charge at 20 kW all day long is 67 (120-(20x2.67)) degrees F.
How about if you want to travel at 70 mph all day and you want to charge at a full charge rate, how cold does it have to be then? If you assume that you are going to charge at 40 kW then your continuous power rate is going to be 26.7 kW; (20 kWh (1 hour at 70 mph) + 20 kWh (40 kW for half an hour))/1.5 hours. The maximum ambient temperature you can maintain this rate would be 19 degrees F; (90-(26.7x2.67)).
If you are wanting to travel a very long distance at 60 mph or more and the ambient temperature is 86 degrees F or more then you are going to have trouble with battery overheating. You wouldn’t have to push your car much beyond these limits to put your car in “Turtle” mode. If you want to travel beyond these limits then you probably need to work on some alternative strategies to keep your battery cool.
Also as I identified in the “Using air conditioning to reduce battery pack temperature” thread, the cabin AC can be used to cool the battery. The cabin air basically cocoons the battery so the cabin air temperature becomes the ambient air temperature in the calculations. But the cabin AC cooling is limited, you can only use the cabin AC to increase your continuous consumption by a few kW but not much more.