Get TierIII items with +3 EES on them (things that your character can wear)
You character starts with 8 EES, add on 9 EES at level 1, you can hold 17 items.
You can in effect put your starting gear from level 1 to 25 on your character, as you level
up in 5 levels each or 10, you can go to town and transfer them over to your mule character
that holds onto them.
Once you get to level 30, you can just get on mule character (remember to equip your EES
gear on your level 30) and transfer the rest of your gear and repeat.
This way you don't need to worry about having a Vault... learn to keep the 3 EES gear in the first
3 slots of your character, anything you pick up will end up appearing last (BUT, always look before
you throw something in trash or shrine).
I have done this for years, currently the vault I do use are just for storing White items for welling
when I come across one.
NOTE: it takes practise to do this safely and not trash/shrine your good equipment. Use at your own risk.