Motor/Controller High Temperature

I have a new to me 2013 EV. I live near Durango, CO. I bought the EV to use in the mountains and on my farm. On the farm, so far no problems. In the mountains...problem. On a 4WD road rated a 2 (only high clearance vehicle needed so not steep and just rough in places) at about 4 miles in the Motor/Controller High Temperature light came on. I was driving in the mid range and had two people in the cab with about 150 lbs of gear in the bed. I let it cool for 10 minutes, drove for ten minutes, light came on again. Gave up and turned around after 3 times. No problems going down hill. Called two dealer maintenance departments and one said check the radiator (grrr, no radiator on th EV). The second said try driving in low gear and blow any accumulated dust off of drive shaft. 2nd try on the same road with the same load but driving in low gear or mid range did not seem to make a difference and we got the same result, although this time we did push on to our destination (11 miles ) with more rest breaks. The 2nd dealer I spoke with said this is something I may just have to deal with. He offered no other fixes.

Is this indeed the way it is for the EV? Or do I need to push the dealer to get in touch with Polaris tech support and find out the fix?

Thanks for the help.