The eyebolts purchased from McMaster are serving me well, of course I ended up purchasing overkill in regards to the eyebolts. After several months, a check of all the attachment points are seemingly doing fine.
The HappiJac camper tie downs mounted on the truck cab are doing well although they are digging into the truck bed some, thus cracking the paint job and deforming the metal ever so slightly. The deformation is minor at this point. I did not install a torsion bar between the bed mounted tie downs. Being my truck is an older model, I'm not overly concerned. However, if I had a newer model truck I would certainly have used the torsion bar in conjunction with the plates. The torsion bar is supposed to prevent that 'digging in' from occurring. Mind you...'my camper is even lighter than all commercial units', so I would certainly use that torsion bar tie-in if I were carrying one of those manufactured units in my truck bed.
Those Stainless Steel HappiJac Turnbuckles are everything individual's claimed them to be and a little more. They are extra durabable and have not given me any problems, they stay tight and the inert springs work as the manufacturer claimed, providing me with stress relief when turning into and driving across driveway drainage configs. Occasionally, I can hear the spring as it is being compressed and relaxed, but this is not a bother to me...Heck, put this kind of load on your back and you just might croak every now and again as well (laughin)
You can see the large, 1/4" thick fender washers and there are 5/16" thick flat iron plates that sit on top of the reinforced area in the interior.