I used to run with a 36"w x 20"h box on my Ram 2015 or 2018 (aisn trans) front hitch rack. in heat of summer I could see a little temp gain on truck gauge in heavy traffic but not enough to worry about.
Forest River Forester 2401R Mercedes Benz.
Sold: 2016 Arctic Fox 990, 2018 Ram 3500, 2011 Open Range
One of my off season projects last year was to install a Torklift front hitch for a Torklift carrier with a 2200i. This hitch mounts high. My summer travels took us over mountain passes without issue.