My happijacks I purchased new for my 1994 Ram tore the sheetmetal in my bed and were not attached to the frame in any way. I understand newer models were beefed up and do attach to the frame now. So this issue is probably moot today.
I purchased these happijacks as people warned me that the Brophy tie downs I was using could damage the truck even though they hadn't. Lesson learned. Back on went the Brophy tie downs on the front. I still used the HJ bumper attachment on the rear. This was on an old 11 foot hard side camper. That worked well for 8 years or so until my old jalopy of a camper was needing structural rebuild or replacement. I chose the later.
I ended up going to the torklift tie downs anyway when we purchased our first high quality camper a Bigfoot 10.6 in 2003. The dealer we purchased the camper from did all the install of the TL, 7 pin in the bed, air bags etc.
It seems that sometimes people have a one size fits all attitude with regards to tie downs. Certainly a small 1000 pound pop up with its low weight and center of gravity does not require the same solution as a 5000 pound 13' tall camper.