So I have the tire size down; 225/75R15 and am looking for just a touch of advice on the wheel.
I believe you mean LT225/75R-16 E.
I have it measured out so matching hub and lugs should not be an issue. I'm a little unsure about the Center cap of all things. I know with the existing wheels the cap is more of a tube presumably to account for the hub itself. Knowing most wheels come with a flat plate to cover the hub I'm not sure if I need a specific wheel.
Most wheels I've seen have a center cut out for clearing the hub. IMO your wheel caps will work fine however your wheel makers or distributor should have all that type of info.