Well it depends on how strongly you want the fruit to come through, but with that recipe I think I would suggest 1-2lbs per gallon. Any more and you will begin to overpower the apple and honey flavors.
I think I would even suggest adding the fruit in your secondary as planned, and then when you rack off the berries, since there will be losses as you pointed out, I would top off with more apple juice.
Meads: Hababero and Sarrano Capiscumel, Show Mead possibly getting split and flavored, and 12 gallons of Bochet Deliciousness
Ciders:3 Ciders with differing additives TBD, Strawberry/Apple Cider
Wine: Black Cherry Vanilla Port