I would think so as well, dually territory. At 42 ft and 18,000 lbs GVWR. That's a lot of RV to tow with a single rear wheel truck, even a 1 ton. It's possible depending on your trucks specific ratings for payload and Rear axle weight rating and so forth but you might be right at the limit.
Don't believe the listed unloaded pin weight of 2,794 lbs, if that is what you're looking at, it's way off from reality. Fully loaded with your stuff and ready to tow and camp, you'll probably be at least 21% of the RVs GVWR for pin weight and that would be 3,780 lbs. At 23% GVWR for pin weight that's 4,140 lbs for the actual pin weight you can expect. Especially if you have a clothes washer and dryer installed up front.
Then add the trucks hitch weight, and anything else that is loaded in the truck and that's a lot of payload for a single rear wheel truck, even a 1 ton. And don't forget the truck rear axle weight rating. It's possible depending on your specific truck, but look at the "real" numbers that you can expect loaded up.
For our RV running fulltime, at 16,800 lbs GVWR and 37 ft we run 3,600 lbs pin weight and that's around 21-22%.