Just throwing this out there but I think there is an alternative way to earn trust level.
That would be to write unique guides/content that is considered helpful for players.
The norm seems to be quantity over quality . Keep posting, do some easy 1 liners for likes and read alot of posts. There is a thread here with the exact requirements.
https://eu.forums.blizzard.com/en/wow/t/the-ultimate-forum-guide-codes-trust-levels-faq/6159
edit* hehe some1 got it already as I was looking ;]