From what I know about truck bullbars and also from the recent installation of my own bullbar, a majority of the strength actually comes from the mount that attaches to the chassis

This will need to be steel the same thickness or bigger than that of the chassis rails. Notice the tube between the rails where the factory nudge bar mounts to. It will need to attach to the four bolts there.

If you plan to fab one yourself, I strongly suggest you see if you can have a look at an accessory or auto parts store that has a winch bullbar in stock that will let you have a look at it

If there was enough interest, I could probably talk custom alloy here in oz to design a winch bar to suit the sportage

www.customalloy.com.au if you are interested to look at there website

If this is not possible, pm me and I will see if I can get a diagram or picture from our bullbar supplier at work to give you a better idea