Mine could actually be a double axle. With the motorcycles onboard I have a little of 12,000 lbs. on the three axles. I have 7,000 lb. axles so it would be no big deal if there were just two axles.
My GVWR is 18,000 lbs, but if you figured 20% or 3600 lbs. on the hitch that would mean there is 14,400 lbs. on the axles so it would be really close if I were loaded completely to the gills, for the axles. But if they have 8,000 lb. axles and 21.5 inch tires, it would be a piece o'cake.
I think part of the thing with triple axle toyhaulers is that the frame doesn't have to be quite as strong since the weight is supported over a longer distance than if it were a double axle. It's probably cheaper to go with 3 axles rather than a heavier/stronger frame. That's my opinion anyway.
Howard and Peggy
"Don't Panic"