Granted, chugging down all the powder isn't the prettiest task to do but I remember somebody here on BL who had a 100g/day habit of kratom leaves.
Extracts might be the first step in switching from H to kratom, but I'm not sure if they can aid you more or just limit the amount of powder one has to swallow. Also usually they're more expensive.
My recommendation would be to utilize the whole arsenal of options instead of relying on just kratom when leaves are too weak to cut it. Use pregabalin/gabapentinoids, ultra-low dose naltrexone, supplements like black seed oil (two options I havent tried yet but I keep reading good stuff about them) to reduce withdrawal intensity and/or NMDA receptor antagonists aka dissociatives like memantine (the best because most clean one) and last but not least loperamide against the diarrhea.
I was on 600mg morphine per day, tapered down to 120mg with pregabalin and memantine, then megadosed the memantine and could kick it without any mayor suffering.