36,000lb gross is the common weight for a 1 ton dual and GN. One could play the numbers game and push 40,000 with tandem 24k axles. For argument propose mine say front axle gross is 5k and rear is 10k for combined axle capacity of 15,000 on my LMM dually. Add a tandem 12k axle trailer (24,000lb) and I could legally plate 39,000lbs with out over loading any of the axles. 40k with LML with 6,000lb front axle.
Most people be worried about stopping.. Since you aren't over load any axle you have plenty of brakes. The problem you run into is cooling of engine oil, coolant and diff oil, transmission not so much due to its in lockup going down the road. I'm 99% sure having sustained 250F and above oil temp is what caused the piston in my 99 to split. Piston got too hot for too long thus weakened and failed at a measly 275-300hp even though the ECT never went over 210.
As for the Kodiaks class 4/5 trucks..I kinda in a away had one the 99 was a class 4 truck. Though substantially lighter than a Kodiak with same cab to axle setup. Rear axles are 12-15k range with 6-8k front axle.. And its 8-9' tall..
With my current setup tare weight on my rear axle is 2500lb with a comfortable 10,000 axle gross, netting a 7500lb cargo capacity. Pending which axle is on the back of the 4500 talking 10-13,000lb cargo on the rear axle. Talking to major trailer companies most freak out about a 5,000lb pin weight.
Having factory 14-15" 4 wheel disc brakes would be very nice.. I figured a 64 or 84 cab to axle setup 4500 2wd is going to push 10k though pending axle rates I might be able to push 45k gross.. At that weight I'd be better of gete a single axle class 6 truck with and a trailer with a 20k axle air ride and air brakes.
Plans Right now with 22,000lb cargo capacity it literally 1/2 the min cargo capacity for.95% of class 8 truck outfits.
I get a bigger truck means I have to bump weight which means I pay more taxes ie fuel and road use tax.
A friend of mine runs 4500 CC 4x4 dodges with 40' steel GN with 24k axles, plates 39k and can only put 17-18k on the deck