With trader changing to a subclass maybe its requirements could be lowered. Or maybe allow a character who otherwise doesn't meet the requirements to become one if they are made Stewart by their liege?
The second suggestion of yours seems like a fine one to me. Its probably not the hardest thing in the world to become a steward now, but hey they will either have probably done something to earn it or made a request to the lord, either way a good thing and if he is a steward it makes sense to allow him to be trader. Trader isn't a very extreme class bad or good atm because of the food system changing so its not really a big deal for a newbie who has gotten himself the position of steward to be able to get the class.
Edited to remove continuance of personal disagreements
