Nvidia Shield Tablet K1 - Best ROM / Official Update Version

I have a Nvidia Shield Tablet K1. With official updates 5.3 & 5.4 having battery life problems even rooted, I am looking for a ROM to help/fix the battery life. I tried LineageOS 14.1 but it seems to suffer the same problems. Right now I am testing Dirty Unicorns 12.0 ROM (Oreo 8.1) which I installed and rooted with magisk that makes Google Play services able to be battery optimized. I am using Hibernation Manager to hibernate the CPU and all apps. Also, using Kernel Tookit for CPU governor. I have set all apps to not use mobile data. If I get any major problems, I will install official update 5.2.

For any Nvidia Shield Tablet K1 users: What is the best ROM and or official update that gives the best battery life and has little to no problems?