I have a F-350 Dually that is capable of towing 16,000lbs. I regularly pull 14-15K lbs.
I have a programmer that gives me a digital display of both my EOT and my ECT.
What would you say is the maximum safe range for these?
If the cooling system is working properly, the coolant temperature shouldn't be any higher than normal.
Depending on whether the engine has an oil cooler, and what type it is, the oil temperature may rise. The safe limit for this is subjective, depending mainly on oil type, but as a ballpark figure a synth oil shouldn't have a problem going as high as 140c.
As long as the coolant does not boil (and your cooling system is in good shape) it is safe to drive.
If you have a 50-50 mix of Anti Freeze and water and a 15lb radiator cap it will boil at 265 degrees F. I doubt you will ever see this max temp.
Mobile One synthetic Motor Oil says it protects up to 500 F, so it would vary depending on brand and type of Oil.
If it has an automatic Transmission, trans fluid temp should no be allowed to go over 200 F.