Back tonight from a great ski trip to Tahoe and saw the many responses to my original post. If anything, that is what my intent was, to get more word out about this issue, feedback, and potential solutions. Too often some confuse me for an attempt to be a "know it all" which is the exact opposite of my true humbleness. I JUST LOVE FOUR WHEEL CAMPERS. I also love the people I meet that have one, especially on the rally's like I just attended. It's that simple.
As for replies back to others regarding this....
Klahanie, yes I did think of somehow keeping the shackle clevis pins from backing out. But I noticed when I had them in my hand that they did not turn very easily once tightened like a normal threaded rod. I then thought I would try to have them angled downward (not always possible) and then check them shortly after I installed them to see if they had backed out. Not a single one had even moved less than a quarter turn. My assumption is that since there is a constant pull on them from an always tight turnbuckle, they have not moved. I will continue to monitor and if anything changes I will tie them. Irregardless, they certainly, like everything in that area, are hard to get at, but not impossible.
Backroad Joe, all my previouse failures were the J bolt side, not a single eye bolt had even began to open. I strongly believe (but do not have proof) that the J bolt is weaker under load. Like I said about chain links, they don't use J hooks to make chains. I think they would be much less strong if they did. My opinion only here, as all these have been. I am no engineer and did not get the "gene" from my father who was.
Vic Harder, as for the Torklifts, I did check into those and they were going to be my last idea if what I did failed. They are so much more $$, I held off pulling the trigger. I also would not know clearance upon trying them out. As I said, space is WAY tight in there and getting access to the spot where you need to install them is no piece of cake either.
pollux, as for truck bed and shoulder, I do have 3 separate rubber mats between camper and bed, I highly recommend them. I think they are what saved me from having my camper slide off when I found my broken J bolts and completely disconnected turnbuckles. I think having the friction from them, as long as you have tightened turnbuckles assists them from loosening. They certainly make for more surface area for the bottom of the camper than the original rails a truck bed has. As for the truck bed shoulder, I wish my camper did sit tight on that, but I cannot change that fact.
Adventurebound, I agree, bed flex is a problem. One guy at the rally found that out after he checked his previously installed camper to find out the screws into the bed had began pulling up from below, an aluminum bed. He went with outside installed turnbuckles bolted to brackets connected to his frame like a full size camper uses. But FWC installed my bracket directly to my frame, a Toyota Tacoma that just needs the original bolts removed and then their bracket installed. I have zero thought of that part of the equation being a problem. The turnbuckles are then installed to their bracket. But I agree that the flexing of the massive amount of weight a camper is, cause turnbuckles (that are not secured some way) to loosen over time. It is the ever increasing slack that causes the camper to rock back and forth more and more until the failure (my J bolts) would practically be guaranteed due to massive amounts of weight being put on the turnbuckle in a short burst of time. The weakest "link" (the J Bolt) I believe, fails first. But in contrast, if you keep your turnbuckles tight and without slack, you keep the camper from rocking and then stressing out the bolts, turnbuckles, (and like me, shackle clevis'). Probably why most do not notice a problem. It's not a "set it and forget it" part that is quite apparent.
CougarCouple, you get the most interesting addition to this post for me. As I was checking out turnbuckles, I quickly realized there is a right hand bolt and a left had bolt. Duh, I know, but like I said, I am a newb. I actually could not find the right length turnbuckle that had eye bolts on both ends that was what I considered, beefy or strong enough. So I bought eight and scavenged the left hand eye bolts off the other ones to give me what I needed. I am sure more due diligence, especially online, would have located the ones I needed. I did not have time for that. But what I did not know or have ever heard, is that installing them the correct direction. With the left/right hand threading it seems to make sense. But then I remembered, I had not paid any attention originally when I installed them, I am pretty sure I probably did not install all of them the same (wrong) way and they ALL had loosed, two completely were disconnected, that has got to be several rotations of thread.
MAC33, I often thought the turnbuckles I looked at did not seem to be strong enough, but I have never seen the chart you presented. But again, mine did not fail, they loosened and then the J hooks failed. I wonder if turnbuckles kept tight on all 4 corners, would keep the camper again from rocking, keeping the load on the turnbuckle much lower that when they are loose and a good jolt given to them by a much more slack one then caused the weakest link (the J again) to fail. I beg for more professional testing for sure.
I think some serious "engineering" testing should be conducted on this problem. I do not have a GoPro, but this seems like a great idea out there for someone who does. Mount one inside the bed, angled at the turnbuckle (hand tight only) and then take your rig off road on something nasty and report back please.
For newbs like me, and all you seriously Learn-ed ones too, we should all be informed, good or bad. I plan to contact Truck Camper Magazine for solutions to this problem. I welcome ANY other of you to help solve the "riddle". Funny how such a pretty cheap item can have such an expensive outcome. But it's not the only one in the RV industry.