I need to supply an average of 5mA for 1/10,000th of a second. I'm charging up the capacitor to 14V (diode drop already accounted for) and it must stay above 12V. So the bare minimum capacitor I need is 1.75uF. I am using a minimum of 4.7uF, but I'm worried about the overcharging thing. 2V ripple is quite a bit but yeah...4.7uF ripple would be around 1V. But yeah...again...
It shouldn't be starving out since the capacitor will only need to support one switching once per commutation cycle. It will have another 1/10,000th of a switching cycle to get recharged (but unlike a bootstrap IC it will be drawing 1mA the entire time from the capacitor since it is designed to run off an isolated supply rather than a boot-strap.