2010 Sierra Scotty HiLander

You’ve indicated that you don’t understand the considerations and dynamics of towing and tow vehicles. And also that your participation in this discussion is lacking. 
That aside, you also haven’t provided other parameters or limitations suck as budget, other intended uses and spatial limitations for the vehicle at home. 
For the vehicle itself, regardlesss of budget etc, your experience or lack therof with both vehicles and towing tip the scales pretty heavily to getting a vechile that is more than capable vs just barely capable. It will help reduce or decrease your risk of doing something new that is potentially dangerous when you don’t know what you’re doing. 

I'd go with simple math on this one. It is true that the curved sections will reduce the effect, but the math for that is complex as well as marginally significant for your purpose. I'd also definitely err on the side of more car than you need for the simple reasons mentioned above: capacity to go uphill at altitude in summer heat. There is a certain level of terror at finding yourself ascending in the heat and slowing down while watching the temperature gauge on the dash climb toward overheat/cylinder head gasket territory as traffic piles up behind you. You definitely do not want to experience that.

There are actually several factors to consider: tongue weight, car payload, surface area of trailer, car towing capacity among them. Towing a camping trailer is akin to dragging a parachute. Experience has shown that often but not always, car payload turns out to be the deciding factor, but you can't ignore the other factors.

This might be a good rime to address the tongue weight issue. You will have about 12 to 15 percent of the weight on the tongue which would put it at less than 500 pounds if it is properly loaded. That puts you in a spot that does not require a weight distribution hitch but does require a hitch that can handle the weight. That you do not need a w/d hitch allows you to look at unibody cars that can handle the tongue weight and tow 4k. You will also need a seven way electrical socket as your rig requires brakes. Remember that even cars have cargo carrying capacity. Look on the door pillar of any car you are considering for the info on that specific vehicle. 
 If the sticker says it can carry 1200 pounds, subtract 500 for the tongue weight and then subtract anything you will put in the car to travel. If you come up with a number that is negative then you need more car. When I was new and getting a first trailer the best choice was a small truck. You might want to rethink your search.

You have a 4klb trailer that will pull like a 6-7klb flatbed. 
Find something good for 6-7k if you want decent power in all conditions. 
Uour intended use, distance, time of year, climate, grades and altitude will have as much bearing as the trailer specs. 
IE it would tow ok behind a midsize suv with 4k capacity in Nebraska on a cool spring morning. It would be almost prohibitively bad at 10kft uphill in the dead of summer. 
Since you don’t have any towing experience I’d say don’t err on the side of barely big enough.