I would add some side bars similar to the ARB's Bull Bars to protect the headlights and marker lights. On this Bumper I wrapped the tube around the side, for better protection.

For steel 1/16 standard mild steel would be too weak IMO, if you want to stay on the thin side go with 3/32 steel diamond plate with some internal gussets to stiffen/support it. If you want a smooth look you can reverse the d-plate, that is what I did for this '86 Bumper , the d-plate does leave an impression on the back side, but a little filler will smooth the stamps out. The '86 bumper came in at about 100lbs, and that is with an internal frame. The one I am currently building for my '91 weighs only 46lbs, I still have the bars and a stinger to add, though I expect the weight to come in under 80lbs.

Aluminum diamond plate will be expensive, I spent about $200 in 5/32 aluminum d-plate alone for '90's bumper , while the '86's only cost me $100 for everyting.

I would design the winch cradle seperatly from the bumper, you would install the winch first and then the bumper around it. The winch cradle and D-ring mounts would be connected to the frame, then the bumper could be attatched to the cradle. This would allow you to use the a small amount of heavy guage steel for the cradle, and the thinner steel for the rest of the bumper. This would also ease in the design/fabrication and installation process, as well as making it easy to repair any damage to the bumper.

To reduce weight, you might consider tapering the bumper with a rolled edge, it will give you the strength of complete sides w/o the weight.