You might be overthinking the weight. After removing the rear hitch and bumper, my custom bumper + swing-out only added like 35lbs. Mine is pretty minimalist, but I still wouldnt expect more than 75-100 lbs added to the rear for even a heavy-duty bumper. And, similarly, adding a 150lb bumper to the front might only add around 110-120 lbs of total weight after removing stock stuff. A winch is another 90 or so with a steel cable, or about 65 with synthetic.
All else being equal, adding 200lbs to a 4500lb vehicle will reduce mileage by a bit over 4%, (about 1 mpg) and maybe a little more on the highway with a real aggressive design that exposes the front tires. Thus, assuming you got 20mpg before (optimistic? ;) ), a 5 gallon Jerry Can still adds about 95 miles to your total range :) .
As to the safety....
My wife hit a tree in her first 5th gen 4runner and completely totaled it. The frame was only very slightly tweaked, if at all, but a lot of the body forward if the doors was pretty wrecked. I am almost positive that a solid front bumper would have minimized damage to the vehicle, by inherently negating most of the factory-designed crumple zones. Would she likely still have been fine? Almost certainly, yes. But, I think it is a little naive--and possibly irresponsible--to assert that solid steel bumpers, which will severely hamper the body's ability to crumple on impact, could possibly result in less energy transferred to the occupants on impact.
That said, I have steel bumpers on my 3rd gen 4Runner and happily drive around with my wife, dogs, and even my newborn in the car. But, I am still certainly aware that, at least to some degree, my modifications have technically made the vehicle less safe (especially in front impacts).
