I would have never expected to be such a huge problem... I am even looking into something called rough cut oak used for tractor trailer beds. I will know something by next Tuesday....
It's not a problem, just a challenge.
If your truck is ever going to be sitting outside, especially in your wet and humid climate I think your choice to go with white oak is good. That species is fairly decay resistant and very durable. Avoid red oak, while it is also very durable, it is much less decay resistant. As I stated before, you are located outside of the natural range of white oak so none of the local sawmills in your area are likely to have that species. You may have to have the boards shipped which will add a considerable cost, but can be done. I found this link to a company I bought lumber from long ago in the past. They list 8/4 white oak, but it looks wicked expensive to me. BTW, hardwood lumber goes by quarter measurements so a 8/4 board equals 2 inches thick.
https://www.walllumber.com/premier.aspAre you certain you need 1.75 inch thick lumber? Seems like it would be overkill and add way too much excess weight. The composite bed (late 1942-43) WW2 Chevy G506 trucks didn't use wood planks that thick, and it was used in a similar configuration as your VB. If memory serves correctly, the G506 used 5/4 (1.25 inch) thick boards.
I live within the natural range of white oak trees and we have a couple of local sawmills that deal with that species. I can hunt for some contact information if you want to go that route.
Happy hunting
