If you bake it properly, you will not get a soggy bottom. Don't be afraid to bake your crostata until the crust is nice and golden. Leave it on the lower oven rack the whole bake time if you need. If the top is browning too fast, tent it with foil. Go by how it looks rather than an exact bake time. I tested this 6 times and didn't have any issues but you need to go by how the crostata is baking rather than the bake time - all ovens are different!