Justification at it's finest, both sides of course. I'll kick this horse again.
The reason for DRW, more capacity, simple as that. You have the same drive train other than the rear axle. Sure they beef up the springs and frame, and adjust the front rear brake balance.
As for a drw being to big for the roads, might want to look at the trucks that built the road, pave the road, gravel the road. Install the electric to the homes. Hint, all DRW.
When a 1 ton isn't big enough they build the F450, F550 or your brands equal. That isn't enough? well no problem, we can all go class 8 if we want/need to.
So that's it, if you need the weight rating you should buy a DRW. If you can axle it out with a SRW go for it. But for my fiver unless they start making super singles you can't/shouldn't try a SRW truck. My DRW barely makes the ratings on the scales and for this discussion the scales don't lie.
My .02