Old truck vs new truck

I own a 2013 Keystone Cougar 5th wheel...loaded up we are slightly under 10k I believe. My current truck is a diesel so it tows fine, just getting old and costly. I see a lot of campers now running newer gas 3/4 ton that tow similar weight to me. I'm leaning towards a new to me gas 3/4 ton since it will be a daily driver...however I do drive a lot. 25k miles a year....so I have a lot of things to think about. The only thing is I live in the mountains, so very I do worry about performance while towing. With my current setup, I just get in and go. I don't worry about mountains, passing semis on the interstate, etc. With gas, seems there is more planning, thought, etc. Guess its all in what you are willing to pay for.