rocker replacement w/ outer tube, or without?

planning to replace the rails. still debating going 3x4 with outer tube or 3x6 without outer tube. Im leaning towards 3x4 with outer tube. If i did do an outer tube, id use 1.5x.125wall, but how would .095 hold up in the rocks?
just looking for opinions. thanks

i just used 2x6....

I did 2x4 and it tucks really nicely into the rocker, all the way to the black foot pads so you add about 3" to your rocker height. if you run with your doors off you don't really need an additional bar to bang on rocks that you might clear without it.