They have stronger hitches you can put on, but a couple things you need to consider...
1. Is your truck rated to pull 15k? The sticker on your door should say GCVW (Gross Combined Vehicle Weight) meaning the weight of your truck and everything in it, including the weight of fuel, other fluids, You, passengers, and anything else that is in it, including bed. And then add that weight to the weight of the trailer and its contents. Does that equal or below the GCVW number printed on the sticker? If it's not, you could be looking at a big ticket if pulled over and/or some damage to your truck, including blown tires or axle damage.
2. Are your tires rated for that weight?
3. Is your rear axles rated for that weight?
There's a reason why Dually trucks can carry and pull so much weight. The combined rating of the dual tires, as well as a stronger axle, are made to do so.
So, anser to your question is, yes, you can put on a larger hitch and yes your truck will pull it. Is it safe? Probably not, but you can do it. You just risk an overweight ticket and possible damage to the rear axle and/or blown tires.
All airbags do is help level the truck, so your headlights aren't pointing to the sky. They do absolutely nothing for allowing you to carry more weight. The weight in the bed and tongue weight still put stress on the tires and the rear axle. In addition, if you have too much weight, are you going to be able to steer the thing safely, as it will lift the front end up.
2007 F250 Crew Cab Lariat 4x4. Lots of upgrades, but not enough. It's tall, too tall. Yes, I'm obviously compensating for something.
EGR Delete, RedHead Steering Gear, Blue Spring Upgrade, ARP Studs, (Let's not mention this manufacturers name) Coolant Filter, (Let's not mention this manufacturers name) Blue Intercooler Pipe and Elbow Upgrade, Cold Air Intake, One-Up Offroad Traction Bars, XD Wheels and Nitto Ridge Grappler 37" Tires, LED Lights all around, 2013 Tailgate, 2008+ Power Mirrors, Pro-Comp XXX Dual Front Coilover Suspension, Custom Bedliner Sprayed Rocker Panels and Fender Flares, Amerihood Tpe E-Style Ram Air/Heat Extraction Hood, CompuStar Alarm with Remote Windows, Remote Start, and much more!
More upgrades to come, including Singer Alternator, and other engine upgrades.
NEW Custom Bumpers with Tire Carrier! Dual Winches!