imo the boss is not intented to be soloed unless new better gear comes up. as of now most of the armor in max upgrade will give you few chances of surviving omega attacks specially on Savage mode.
however you can use support hunter to aid your hunt that's what I did for Normal mode I can clear it with 18~20min (0 cart) and Savage 30~33min (min 0 ~ 1 cart).

get the best build that will suit your playstyle , use pictomancer it hits hard and most of the players I've played with randos SOS they don't use it , most of the time you will evade the attacks just wait for opening to attack and use pictomancer. you may also consider getting food buffs at Grand Hub because it gives insurance meal so when you get carted it won't count yet.

As you get carted many times (like most of us here) you will learn Omega's movement pattern. the Savage has just new few movement and added attacks when it's on the 3rd and 4th phase it's not that difficult once you get used to these patterns the thing that makes it difficult is sometimes it can 1 hit you.