That sounds like a fine plan. I made the same mistake once, and I have the following advice: You extracted WAY more IBUs than intended with your lower gravity wort, so you're going to have to age this for a LONG time before it's not horribly bitter. Don't give up on it - in a few months it'll be great, regardless of whether you add the boiled DME or not! (I opted not to.) If you do add it, make sure you boil it thoroughly to avoid nasty dms flavors.
Beauty is in the eye of the beer holder.