I think you will be fine on weight.
The tires and wheels are more of a limiting factor than the axle.
E rated tires are 3590 lbs each (roughly), so on an SRW, you are good to 7k on the rear axle.
Not necessarily that you would want something that heavy, but a Lance 815 is just fine.
You will find that that it is quite a common occurrence (notice I don't say problem), to NOT exceed your axle or tire weights, but to exceed your GVWR.
That's because most of the time, the GVWR is smaller than the FGAWR and the RGAWR addd together. Seems weight, but that's the way it is.
In some states, you can't even register your truck for the exact GVWR, so the number is pretty meaningless.
What matters is the tires and wheels, they put the weight on the road.
