Had a similar issue with my floater hubs. I have Formula 43 RAD 14's and their caps are very similar with the O ring attachment. I didn't have enough room around the hub and the wheel, so I ended up machining some new axle retention plates, engraving their logo on the plate and getting them powder coated to match. Your Forgelines will look great using the same concept. Have the dust caps all but the same size as the ID of the wheel (no bevel on the edge) and they will blend in neatly.
