I tow about the same weight boat with just a 24" extension bar. It is not the most conservative approach given my 13 year old 2" OEM receiver, but it's made it 10-20k miles of towing the boat and a heavier trailer to AK and back, for comparison.
Guessing your camper is around 3500lbs ready to camp.
You're putting a lot on the back of the truck. Do-able and the axle and chassi are more than up to the task. Tires, wheels and suspension are what you're upgrading.
I'd get a sway bar, wedge the lower overload spring and then add bags, Timbrens or add a leafs. Like super springs.
Hitch, conservative solution is the big hitch you mention. Likely cheaper than extending the trailer tongue. Plus then you're ruining the trailer for future owner who doesn't need a "custom" trailer tongue length.
Weigh the cost of the options with how long you'll keep that truck and make sure your doing the right thing, unless budget isn't a huge concern.
