Is Challenge difficulty unlocked for missions in WT2? I wasn't paying attention when I was there.
If so, that's your best bet. Make sure you're wearing 320 gear, because what you wear influences what drops for you.
Also, field proficiency caches drop gear with a gear score at or above the recommended for the stronghold.
You dont have to wear it do you. Just keep your highest gear score stuff in you stash will do for drops.
Nikki posted on their twitter:
https://mobile.twitter.com/Patt3rson...49740209717248
GearScore for loot drops is based on your max attainable own GearScore from all items owned, including your stash. Just hold on to items with higher GearScore, you don't need to equip them to still get better drops.