With the proliferation of Lite and Ultra-Lite campers, frame and bumper strength as a function of "overkill" has resulted in a frame that "does the job" as shipped, but not a whole lot more.
Modifications that go beyond the designed intent need to be carefully thought out because the OEM frame may not be capable of supporting the designed life expectancy after the modification.
For example, adding weight at the very rear of a camper not planned for in the placement of the trailer axles, can result in frame flex beyond that which can be sustained for the planned life expectancy (frame flex cycles).
This also applies to camper/TV GVWR as well.
To get some idea of what frame flexing does to the metal of the frame, a coiled metal paper clip will give you some idea. (This is a great exercise while watching paint dry or listening to the In-Laws explain your faults).
Open up the paper clip so it is a straight as you can get it. Holding the ends, flex the paperclip back and forth VERY slightly. The idea is not to bend the paper clip at all, just flex it. Count the bends and when it snaps, record the number of times you flexed it and where the paper clip broke. (Repeat this exercise as many times as it takes until they shut up.)
After a bit you will come to realize that the location of the break is pretty random, but the number of flexes is pretty constant (provided your flexes were pretty constant). The larger the flex transients; the sooner the break.
You will also realize listening to the In-Laws was not so bad after all while doing this research.