I think there are air bags and anti sway bars that can help you, but... wow, you've got a big fifth wheel. How much does it weight? You should post this in the towing section - you will get more responses from people who actually tow and can give a good advise for your set-up. That's what's great about this site.
Air bags, helper springs... it's all parts and money. Someone's life - that's a different story. With that being said I hope you make a good decision, be safe on the road, and keep other drivers around you safe too.
Ilian