I don't know what your strawberry filling is made of, but on tv, I see them swirl some icing (or filling or something, then add berries. I think it helps hold the cake layers apart and give the berries something to stick to.
They draw a circle swirling from the middle of the cake layer to the outside with space in between for the berries. Of course there is a dam.
the thickness of the dam is often the size of the opening of the coupler. Just tape across the break in the coupler and use that to pipe the dam and the swirl, or use a huge star tip.
I like to get raspberry preserves--like "allfruit" strain out the seeds, and spread that in a thin layer onto the cake, then use the cheesecake filling, or pastry cream on top of that. I have got a lot of good response from that.
that is from my son. He always asks to add a smiley. Is he 2 yrs old? No, 13.