Update- I made it!
Here is the followup on my trailer hub heat question. I made the 1000 mile round trip to Canada without incident. The hub temp is more dependent on the air temperature than I would have guessed. The highest heat measured was on the way up at 143 degrees when the air temp was 86. It got cooler as I went north. We went through a front and when the air temp was 63 my hub temp went to 98. The reverse was true on the way home. As I drove south and the air temps climbed the hub temps went up reaching 140 when the airtemp was 84. For the record I don't think I drive hard, no more than 65 on the interstate. I have occasionally measured the temp of the brake rotor when I checked the hub temp and it has usually been less than the hub temp. Thanks for all the opinions on my question.