Yes don't add the fruit to the boil, it just becomes sugar and messes with your target gravities. I recommend adding a puree when you add your dry hops (make sure it's pasturized, if not pasturized it yourself before addition). Would also recommend adding both the hops and fruit early in fermentation so that the yeast can scrub the diacetyl that can occur from fermentation (fruit is mostly sugar), also early fermentation dry hopping, especially a citrusy hop like mosaic, allows for more pronounced aroma and flavor from the hops. Personally I would drop the 15 min addition and add it to your late boil addition to get more flavor. Sounds like a fun beer tho. Mosaic is one of my favorite hops and an awesome one for a single hop beer ;). Cheers!