That far out of warranty, I don't know if I'd hold out hope for the factory to do anything for you (talk to the ambulance chaser).
Are there any heavy items that can be moved from the slide out side to the other side?
I'd also be looking to see what other tires you could use that wouldn't be overloaded.
Lastly, what axles are under the trailer? Mine has Al-Ko's rated at 5200, even though the trailer's axle weight rating is 10,000, so I guess they built in a little safety margin.
If it were mine and I ended up dealing with it myself, I'd look at getting axles of the next higher weight rating. A pair of axles with springs might be less than you would think, and to me replacing the broken spring with one just like it sounds like it might be a temporary solution at best.
Anyway, good luck with it, and welcome to the forum.
Dodge Ram dually laramie 4x4 w/jake, B&W, Brakesmart.
Kit Patio Hauler 394F toyhauler 5th wheel
Camo 680 Rincon, Green 500 Foreman, Blk twincam Roadking