Adding steeped, roasted malt to keg?

I just made an oatmeal stout and it doesn’t have near enough roasty flavor for my tastes. In fact, I used s-04 for the first time and all I really taste and smell is the fruitiness from the yeast (Fermentation got up to 70 near the end of the 2nd day, then slowly came down, FWIW).

Anyway, I want to add maybe .75 roasted barley to this to give it some more flavor (or at least something other than fruitiness).

My plan:
cold-steep .75# Roasted Barley in about 1.5L of water overnight
boil for 15 mins
ferment for a few days in a growler with US-05
decant and add to an already carbed keg.

Does anyone foresee a problem with this, or does anyone have any experience with this?