1. Mano sankhara still contribute to akusala kamma (because they get generated due to avijja).
– However, those are “weak” kamma and do not lead to rebirths, i.e., they are not abhisankhara.
2. The way to ultimately control mano sankhara is to control vaci and kaya sankhara and thereby reducing one’s bad gati.
– That is the key to Anapanasati/Satipatthana.
I have revised the post “Ten Immoral Actions (Dasa Akusala)” to explain that.
– More details are in the post, “Correct Meaning of Vacī Sankhāra” referred there.
All ten types of akusala are done with saṅkhāra via “avijjā paccayā saṅkhāra.”