If you raise the bed, you can forego the need for fenders and have a completely flat deck.
I wouldn't use angle iron, it is heavier than you need.
If you have access to a welder you could go w/a flat frame like this,
then use what ever boards you wanted to for the deck. Just don't use the OSB board that the poster on Yotatech used, as soon as that stuff gets wet it separates.
