I've kept several T. maximas, several T. croceas, 1 T. squamosa and 2 T. derasas, under T5HO for up to 4 years. Color never faded at all.
With individual reflectors OR ICR (individually contoured reflectors) and with enough bulb coverage, you can grow anything you want, under T5HOs.
However, I do not feel that your 4 bulbs are quite enough. If you do try it, I'd suggest Derasas, as they're the least light demanding. They're also a sand dwelling clam. If you go with Maximas, they're rock dwelling clams, which is good, since they're also more light demanding and you can put them higher in your tank. Also, flow is important. They need to be protected from a lot of flow. If the flow is constantly buffeting the mantle, it's too much flow. If the mantle is gently flickering, once in awhile, and still most of the time, you've got the flow just right.