The rear steel L bumper weighs about 21 lbs. The fibreglass aftermarket bumper 9really just a shell)that some of the vendors sell weighs about 6 lbs. Pantera East sells a fibreglass unit that has some reinforcements in it that would probably weigh more.
The custom bumper trailer hitch that I made that fits inside the aftermarket shell, weighs 25 lbs, so when the hitch is installed, I have a net gain over the stocker of 11 lbs. The hitch removes with 4 bolts. I bought a motorcycle trailer, (the type that gets pulled behind a Gold Wing) that I intend to pull behind the P-car. I am getting the trailer back this week and going to a show this weekend, I will post some pictures next week.