Here's the tab:


Instead of this:


This is at the back of the bed near the cab. This is where one of the bolts goes through the wood. I'm just going to bolt it to the frame without bolting it through the wood.





From underneath - this is one of the two middle crossmembers that usually has a bolt running through it to the top of and through the wood:


but instead, I just bolted it to the frame, and the bed wood strips will bolt to the crossmember, tying the wood together with something substantial.

One of the 2 bolts that hold the rear of the bed to the frame:

 

I assume you aren't going to put any substantial weight in this bed? I wouldn't trust those spot welds on the cross sills to hold up to real work for the next 50 years.
I understand the concept of show trucks(heck, I build them for people every day), but feel like Ford put a lot into the engineering of the trucks and that's why they're still around today. If I was building a work truck, I'd assemble the bed as the factory did.
You want it to look good? Buy stainless hardware and spend a couple hours polishing it(or buy it pre-polished, I'm cheap like that).