Gas vs Diesel for Towing a Fifth Wheel!!!

I made the mistake of buying a new 2006 f350 diesel with the 6.0 engine. I sold it last month and bought a 2017 f250 6.2 gas truck. Out 5th wheel loaded weighs 10,000 . The 6.2 does a fine job pulling and to be honest I didn’t want to drop another $9000.00 on diesel. Our new truck is a gas hog, however here in California Diesel is $.50 a gallon more than gas, so it almost works out the same.
Our old Diesel only had 79,000 miles when I sold it. It started to overheat on steep grades and I got tired of cleaning egr valves. It would have cost $6000.00 to 8,000 to bullet proof it.