towing thru Big Horn Mountains in Wyoming

We did Black Hills and Yellowstone last year and after I had researched doing 14 or 16 through Big Horn Mountains, I decided against it and we went around using 90 to Billings and then back tracking to Cody, WY. I like you had a Silverado 1500, towing package and transmission cooler, and a 29' trailer, but I was running pretty heavy though. We entered through Yellowstone east entrance, at the top my transmission temps were at 225 and the outside temps where 45 degrees(mid July).

Good Luck and please report back how it goes, I think that will help others make choices.

thanks,
Dean