I cannot say I have found I do particularly well when I have tried evenly split hybrid AP/AD builds but I very much agree that MF benefits from both. My primary concern is the runes you selected. It is not very efficient to use AP for all the rune slots, for Red Marks I believe the magic pen/armor pen runes would end up giving you more magic/physical damage instead then you could get from the 16 AP.
Also I think with this build the ultimate would still be using AD as the bonus not AP as its 20% of AP and 50% of AD and you still have more AD than AP. So the AP is only going to help Make it Rain and Impure Shots
Feel free to swing by My Fortune Build I do take some AP although its only through one item. I found the Ultimate scaling primarily with AD make her feel a bit weaker in hybrid form

in this sense, his ultimate is not as good as a MF AP or DPS, but the Impure Shot with AD for quite some damage, and all his skills do enough damage, less than one AD or AP, but uses two

Could you explain, why you think that Hybrid is superior to AP or AD?