Anchor points for truck bed

[HunterSmithing]

Hello everyone. Just joined because I’m not getting any luck using Google. I want to add anchor points using d rings. I have 4 points already but my tool box makes the front ones hard to reach. I did put two in the top middle holes of the truck bed. Their the husky ones you’ll find at Home Depot. They’re only rated at 333 work load. That’s not going to cut it and I rather have my anchor points lower. Has anyone added these to their bed floor? Some YouTube videos say use self tapping screws. I rather use a nut and washer if possible. Thank you in advance