Sprinter diesel tow question

I tow a 4500lb 2016 Wrangler JKU with my 2018 Navion 24V on a 2017 Sprinter 3500 chassis. Loaded for travel the combination is close to the max GCWR, but it works. A 2-door Wrangler would be easier, obviously, as it's a lighter vehicle.
Like way2roll says, you have to get everything weighed loaded for travel, accurately, then do the math.

I have a older one 5cyc 2007 pulls my 18ft boat to AZ 3rd gear in steep mountains. p.s and I get 17mpg doing it.

For a technical answer you really need to run the numbers. Weigh the unit loaded for travel (water, food, people) etc and subtract that from the GCWR which will leave you with your towing capacity.

I am surprised at how well our new Sprinter class C tows our CRV. The brakes on the sprinter are awesome (much better than our previous gas class A's). I do have supplemental brakes in the CRV though. The Sprinter has a good deal of low end torque so taking off is no issue. My only complaint is climbing hills at highway speeds and passing. 60+ MPH towing a car and the sprinter doesn't have much left in terms of acceleration. If you want to maintain 70MPH on the interstate and pass a truck going 68 - it will take about 3 minutes - no joke. But the diesel based class C's otherwise are very capable of towing a car provided the numbers are within specs.