The really short answer, build the structure tucked in and skin it with a decorative stock bumper. When I got my last one there was thick steel hidden behind the stock bumpers. I took the chrome bumper off the front and just welded an old Bellview winch on at first. For the front the biggest issue is often just figuring the packaging without getting into the radiator. For the rear I remember a guy made a nice hitch that was tucked in really nice, so nice that he couldn't get the pin in. And there is a gas tank that keeps you from tucking stuff in too much.