Towing 5th Wheel with Lowered Dually?

[rsjohnsn]

I want to lower my 2008 F350 2 wheel drive dually and install big rig wheels and tires. I need to know what I am looking at as far as bed rail height difference compared to stock. I have a 5th wheel RV and a goose neck trailer that I haul and my 5th hitch is set to it's highest setting now to make the RV sit level. Can I do this and still be able to haul level or will the trailers be nose down?

Thanks
Scott