Payload is an important number as if you are not careful, you can exceed the weight the car/truck was meant to CARRY. Think of it as how much stuff you can load into your car without overloading the suspension, etc...
I was one of those guys that thought "oh, my suburban with 8600lb tow rating can easity pulll our #6500lb RV." 20 min down the road I knew I was in trouble. Suburban felt like it had two flat tires. Sadly, it only had a pitiful 1425lb payload capacity.
-700lbs for 2 adults, 2 teenagers, and 2 kids
-150lbs for 2 kayaks
-??? for 6 bikes
-??? for etc
you can see you can get into trouble quickly with a 1/2 truck. Our 3/4 ton truck sits happy with 2300lb payload capacity.
We had a 2003 Subrban LT with the 4.10 rear end.
Pulled our 3600lb PopUp wonderfully.
When we upgraded to our #6500lb Hybrid, it was awful. The Suburban was rated to tow something like 8600lbs...but the payload was a pitiful 1425lb.
With 600lb on the hitch, + two 75lb kayaks, and 6 bikes, 4 kids, etc etc...the Suburban's comfy-minded suspension was overloaded and the rear end felt like I had 2 flat tires all the time.
Needless to say, our 3/4ton ram truck does a great job with our current RV.
Welcome to the forum..and welcome to Camping High & Dry!
Don't fret. Common mistake. Heck, my dealer told me I could tow my 23' Hybrid with my Suburban. NOT! After 20min down the road, I knew it was too much for the Suburban's mushy suspension. Plenty of Towing capacity (your 3500 number) with our old Suburban, but very poor on the PAYLOAD capacity (you will find this on the driver door).
After your "test drive" I would seriously think about the kind of mileage you will put on the camper. Zipping around the local area for a few miles is one thing...but treking for a 1000 miles could very well put your minivan into an early grave. If your towing capacity is 3500lbs, I would consider a 2500lb camper...max. Or...get a bigger tow vehicle.
We used to have a 3600lb pop up, and my Chevy trailblazer (w/ 5000lb tow rating) was screaming in 3rd gear all day long to keep it at 65mpg.
When you add all the camping stuff, and people in the van, with their stuff...the weights add up really fast!
Here is a pic of our passle of 4 sleeping on the floor. Mom was on the slideout dinette and dad was on the couch. We were "turtling" one night (i.e. no bunkend were out).
its tight, but if you put the bunk ends out, you can then put 2 in each bunk end, and there you have 10!
My 2011 Ram with Hemi and 4.10 rear gets 13mpg around town, and 15mpg on highway (70mph or less).
Towing she gets 9'ish, but our camper is smaller than yours.
With the 4.10 she is rated to to 11,400lbs. see below.
5.7L V8 gas (EZC) A5 545RFE 5 sp AUTO (DGQ) 4.10 8,800 2,360 6,440 3,685 2,755 5,200 6,010 18,000 11,400