The tiedowns install in specific locations on the truck, and the anchors are in fixed locations on the camper. You're pretty much going to end up with what you end up with.
For sure your camper isn't going anywhere forward. Rearward would be your only (minor) concern.
If your truck bed is so slippery that you are worried about the camper sliding out when you take off, do something about it. Put something less slippery between the camper and the bed. I think the tiedowns are primarily for vertical stability, not fore/aft/side.