I don't think there's a sensor for engine oil temperature so don't blame edge, but there is a sensor for CYLINDER HEAD TEMPERATURE. I have the MSD Dashawk, which I think is discontinued now. I found that my transmission temperatures got just as hot with just me in the Expy in stop-and-go Phoenix traffic as I did fully loaded with the family pulling a 31' travel trailer (13,000 total weight) up hill in 110°F heat!
Do yourself a favor and weigh your trailer and truck. You can use a truck scale for like $8 or most gravel yards will give you a free non-certified weigh.