On previous 2x trucks I have owned, I built a small 2x4 frame between the wheel wells similar to your description. I dropped in the bagged sand and put a plywood sheet over to act as a flat floor. I think the only thing you need to worry about is maintaining a balanced load that will not shift on turns or inclines. Your framing should prevent the load from shifting. Having a load shift on slippery roads could cause increased excitement!

 

On the slip from the factory on my 4x2 Ram it had Anti-Lock differential as part of the ST package group. Can I assume that's a LSD?

And just so I'm sure.. LSD is when one tire won't spin on its own, but uses clutches to force both to put torque on the pavement, right?

 

You probably meant "Anti-spin"? Yes, it's an LSD, unless it's a 2500 or 3500, then it's a true mechanical locker.

 

I'd agree with these guys that a 2wd would probably work, but if you can afford it the 4wd is the way to go. Also (this is on some other threads) the 04's on tell you not to do a plow on a 1500. Don't know if anything would actuallly go wrong, but if it did, you'd be stuck with no warranty, so best to go 2500