For those flake powders, there is a region I have marked on the side of my Dillon powder measure (two marks) where I try to keep the powder column. As I load and the column slowly comes down, when it hits the lower mark, I fill it back to the top mark. The two marks are about 50-60% of the full powder measure cannister and the two marks are about an inch apart.
Another thing I have added to my powder measure is a baffle that mitigates that changing weight as the column decreases in height. It is made of thin sheet aluminum and is cut to partially block the weight of the powder column. The baffle only blocks about half the area of the cross section of the measure cannister.
Lastly, as I hold the press lever down on the powder drop step, I tap the side of the powder measure, so that the column settles and lose flakes drop free past the baffle and the cut off.
These tricks help a lot with my Herco and Blue Dot loads.
Hopefully that will help with those very light flake powders. BTW, I got these tips from a reloading manual. 'Got a couple?