I'm gunna assume you're making a 5 gallon batch. I would do half apple half mango, since mango is somewhat of a subtle flavor I would ease up on the added sugar and maybe shoot for a final abv of around 6-7% and, if you have any, definitely add a pound of maltodextrin for body. Add all the juice and frozen fruit to your carboy, add any additive you like to the juice, and pitch your yeast. Keep it simple and you won't be dissapointed. You will prolly need to rack at least 3 times buts that's alright. If I were you I would keep adding fresh fruit to each subsequent racking to keep the flavor building as well as topping off only with mango juice/nectar. Think of this more as a wine that will be carved than a cider.
Let me know if need more detailed info, I'm on a train and feeling pretty lazy after work. 😀
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