Make sure the weapons, traps, etc aren't trade-able. I also advise you not to make a gang bank, because the leader can have let's say 3 extra player accounts along with their real one on at the same time. The leader basically gets an advantage by having 4x the amount of gp for very few effort. Also, leaders could charge their members 25% of their Gang points to stay in the guild or rank up faster. Unless you wouldn't mind these things, then you shouldn't add a gang bank.