Climbing anchors are intended to have the loads applied in a direction close to parallel with the surface that they are mounted on. The worst possible placement for a "bolt" (as they are called) is one where the load will be perpendicular to the surface. This is due to two concerns. First is that the strength of such a placement relies entirely on the pull-out strength of the anchor (which doesn't really apply to our use). Second is because the nature of the design of the tab results in an eccentric load which applies a compound bending moment against the anchor (which does apply and can be a significant concern).
For holding light stuff down in a p'up bed it's probably OK. I wouldn't suggest using them to hold down a camper as they will always apply a compound bending moment. A forged eye-bolt need only be aligned properly to any angled pull to reduce it's applied bending moment to be very small. I used some of these in the galvanized 1/2" size. They have 4" square, 1/8" thick load spreading plates under the bed, then a heavy flat washer and a nylock nut. Wanting no sharp edges or corners to act like a can opener against the bottom of the bed I also rounded the corners and radiused the top edges of the plates.
http://www.mcmaster.com/#general-purpose-eyebolts/=kj5xmk
I understand what you're saying with the direction of which they are being pulled and thought about that thoroughly. With my particular camper/turnbuckle set-up the angle of the turnbuckle from the camper to the truck bed is by no means pulling straight out on the bolt hanger. It's at about a 45degree angle, which on overhanging rock climbs is pretty close to the direction of pull if one were to fall on a bolt. The bending of the tab in the bolt seems to transfer to the backing plate I installed, not the wood or steel. Also the mcmaster website warns about strength of eye bolts being significantly reduced when pulled at an angle. I'm sure the eye bolt won't break, but it's going to transfer that stress to what it's mounted in. I'm not trying to argue with you, I just work with bolts on a daily basis for my job and have seen bolt hangers severely stressed (in rock of course) in multiple directions and have seen nothing that would convince me an eye bolt would preform any better. All I see with the eye bolts is a taller anchor point and increased leverage. Obviously the surface you're mounting the eyebolt/bolt into makes a difference but in the 6 months of living in and out of my camper driving into extremely rough trailheads I've noticed no bending of the bolt hangers or surfaces they're mounted in. If you use a good enough backing plate it shouldn't be an issue either way.
