GM quit making the 5500. The Ford F 550 is a comparably unit we used to get them with 19500 lbs gvw in the long wheel base. You can get an International with up to 33000 lbs capacity in Canada on single axle with hydraulic brakes. You still drive it with a normal drivers license. It also sits on 22.5 tires so it has more ground clearance than the Fords and Chevs if thats an advantage.
How many hives do you haul at once Jeff? The other issue to consider is some of these new trucks have a large and very hot exhaust system, if your in an out of dry areas I would look at the clearance and or a shroud of some sort.