Duramax Engine temps while heavy towing

[rblanch]

Have a 2020 3500 srw crew cab long bed duramax. I tow a 17000 lb gvw toy hauler. Since the truck was new I never noticed the temp gauge go much above the 180 degree mark. During the summer we went on a long trip out west and I noticed while towing the temp gauge is constantly going up gradually past the 210 mark and then back down to 180 in New Mexico when it was 106 degrees outside it got up to about 230 once the back down to 180 the dealer says it’s normal I was wondering what temps others are running ing in hot summer while heavy towing