Thanks to @medtro, center caps installed on my new tundra rims. I used a crude mod technique (removed metal ring, removed one of the clips, the others snapped in pretty snug). Hopefully they hold at 80mph and on switchbacks. . .
I don’t mind the mismatched front and rear caps - I prefer the flatter tundra caps overall so I will leave them on the back. That also allows me to store 2 of each in case of loss or damage.
Running Cooper AT3s now. Quite a noise and ride improvement over the mudders that were on it before at highway speed.
Now I need to decide if I am going to keep the running boards.