I know caapi is best on empty stomach for most uses, but for microdosing, does it matter overall? Does overall does the same amount get absorbed over a stretched timeframe, or is it wasteful with food in my stomach?

Well fasting some part of the day for daily microdosing on an empty stomache isn't really feasible. If you want to take it on an empty stomach you can just take it first thing in the morning. I really enjoyed taking around 5-10g caapi in the morning and at night. With the price of caapi these days i usually just use rue or extracted harmalas for microdosing though.