Hey, wamille, I know what you mean when you say you're using the artists approach. On the other hand the engineering part is like an artist learning technique before he can truly achieve all that he set out to accomplish. Yes I think you should add hops after the thirty minute mark, IF you want some hop character. You will have so much malt character that your current plan will result in no noticeable hop character other than bitterness. The sixty minute addition will result in zero distinguishable hop flavor, and in this beer the thirty minute addition won't amount to much either (depending on the size of the addition). It sounded like you wanted the berry character of the pacific gem, if that's the case use the simcoe for your 60 min addition and use the pacific gem between 20-10 minutes. Or for a subtle flavor from the simcoe add some at 60, some at 20 minutes and then the pacific at 15 minutes. What size of hop additions are we talking about?
Your choice, your beer. This is your beer and you should do whatever you want. That said; the debittered black and carafa will come through as less bitter versions of the black malt. So you have 2.25 lbs of black malt (with 1.75 lbs being less bitter). Might be a bit much, your choice. Also the carapils will be a flavorless addition of body something this beer isn't lacking. Want to use flaked barley, oats and rye? Ok but that's a lot of unfermentables thus a lot of body; maybe cut the additions down a little. Even using a pound total would give a nice graininess (you won’t be able to pick out their flavor in this beer) and give a boost to the body. In case you haven’t already read, “Designing Great Beers,” it’s an excellent book and is very helpful with rough guidelines for the creation of a recipe. Cheers, j