The items I carry in my bumper box are not very heavy. I carry a hose, a 30 amp power cord, 4 wood blocks, a little plastic tool chest with the basics, and a hammer. Oops forgot the two poles that hold up my front rock shield.
Below the bumper box is a 5"x5"x 4' plastic fence post that contains my primary sewer hose and a rubber donut.
Below the fence post I carry 3 pieces of PVC pipe that create a rear clothes line.
It simply carries things that belong outside. As well it wraps around my spare tire.
I've never weighed it but I'm positive it's not excessive for any bumper.
I used to carry a second hose and filter and a 50' extension cord that I have moved to underneath boxes because they're rarely used.
Norm and Ginny
2004 Honda CRV
1991 Scamp 16