It's not a loose turnbuckle issue. I have never found them loose in the 15k miles I've hauled this around. I think it is really just not an ideal tie down system and thin truck bed. Nissan does show in the manual that you can use a truck camper but they do not show how to secure it.
Before my FWC I had another brand with frame mounted front tie downs, obviously there were no problems with the bed, but it would be in the way for off road use. Additionally, I am now taking it off road.
I'll just keep checking it, knowing that I will need to weld something in place down the road.
My dealer (MainLine Overland) took care of it at no charge about 10 months after purchase, it is nice to know that they have my back.