Opinions on my dilema - newer trucks SRW vs DRW

I carried my 4,000 pound TC on a Chevy 3500 SRW while pulling a 4,500 pound boat and trailer. I did this for 2 years. Then, I switched to a Chevy 3500 dually; same camper and boat. The difference was amazing in just a very few miles. There was far less bounce and sway. The whole rig just felt more solid. I knew it would be better but I was surprised how much better and how quickly I could tell a difference.
Get a dually. Then, if you want, upgrade to a long bed camper.