Here's my view point on it. I stocked RBT and in great enough numbers they will eliminate the FHM. I think the RBT will then go after the YP as the next best option, if the RBT are allowed to get big enough(14" and bigger?). At the very least, I don't see any reason why they wouldn't want the YP fry. This leads to what I see as the problem: what are the YP going to eat if all the FHM are gone?

Are there any plans to feed?
Will the trout live year long?
Can you source feed trained YP?

If you feed, The YP will benefit but the RBT will be lazy from getting the easy meal and not manage the YP enough. You could periodically stop feeding and force the trout to go after the YP.