While possible to boost with extra controllers you can also do this with bots. Vs AI it is best done in a short game so the AI gets less overall gear as an advantage.
Your primary goal is to sell as many items as possible, loot chests, and complete the stage goal which is usually to pick up ducks. It is important to avoid combat as much as possible since you won't have strong weapons or armour and the AI tends to struggle vs the enemies early on. In particular I was able to let the AI distract the enemies and sneak around to sell loot cards from chests.
I recommend the elven race since speed allows you to get around enemies and loot quicker than the AI.