Thanks for the tip but my trans is still full up. As long as it cools down when the load is reduced everything is working fine. Living in the desert we see a lot of 100+ days and I replaced the trans fluid with pure synthetic which certainly helps.
I can't imagine running without a Scan Gauge or similar device to monitor coolant and trans fluid temps. By keeping the trans in Tow Haul for about 90% of the trip the V-10 and Torque Shift tranny stay happy and even running near our 11,500# GVWR and towing the 960# trailer/bike combo we are getting our usual 9.5 mpg.
:C