We had a '15 F350 SRW,CC,4x4,SB,6.7 and thought it would be our last truck. Despite being a off the lot purchase, I really liked it. Bought in Dec '14. Come '17 , we decided to get a new RV.....Big Country 3560SS (empty 14k, max 16k). Scaled out, the RV weighs 16 k fully loaded. Like what's already been said, it was at the limits of the truck and in some cases over. Overall, it did ok towing it with the tires being the weakest link.Then in '18 our vacation plans were taking us to FL in Aug. Knowing we were already maxed out and the tire situation wore heavily on my mind. So we ending up getting a '17 F350 DRW,CC,4x4,6.7. Really didn't want to, but in the interest of safety, did it. Doesn't get as good as mpg's as the '15, BUT it DOES tow a whole lot better. The wife said she felt more comfy driving it when towing VS the '15 and she doesn't tow hardly at all. She really does do a great job when I have to take a break. I'm currently grossing around 24,000.
So could I still get by w/ say a 2023 SRW? Perhaps given it has higher ratings than the '15's did, however, think many will still say that anything north of 16k is DRW territory. Not saying you can't, but it's MUCH safer.
IF your on the fence between a 250 or 350, go with the 350 due to higher ratings from the get go. It's possible you can be at the 250's rating really quick like. Just my $.02.