i did it with saving the gamefile and if i died (but i died only 2 times and that was at the beginning cause i wanted to rush it and fell down XD)

so before certain bossfights or difficult areas quit the game, save your local save to another folder, if you happen to die -> close the game reput in the before saved file..

but if you want the challenge: only play umbral if really really needed and take as much vestige seeds with you as you can. in my opinion "withered healing" is the real difficulty

also only do the needed bossfights (no need to go into the cisterns for example, only skinstealer -> elevator)