Would frozen fruit work in place of fresh?
This question references CHOW's Slow Cooker Peach Crumble recipe.
I haven't tried that recipe, but I make crisps with frozen fruit all the time. You can either just use it frozen or you can defrost in the fridge first. If you defrost it in the fridge first, do it in a colander over a bowl so the liquid drips down and you can discard it.
If you don't defrost first, you should add 15-20 minutes to the baking, and also know that it might be a bit more liquidy. You can add a 1/2 teaspoon of corn starch to prevent that.