You don't say what year your Durango is, but the 2020 version is rated to tow 6,200 to 8,700 lbs. With the "tow package," I'm guessing you are on the higher end of that range.
From what I see, the Forest River No Boundaries 19.8 has a GVRW of just under 5,000# so you are certainly within the tow ratings of your SUV.
"How they are as pull vehicles..." pretty much depends on the individual user. Some SUVs have a short wheelbase and cause them to have a bit of a choppy ride when towing, but I've never towed with the Durango, so can't give you a first-hand evaluation.
TJ