I would advise to extend the loan or try to borrow from friends/family first.
But if you REALLY want to risk it. use the $200 on super high leverage on Bitmex.
If you are lucky you might make that $5k but its super super risky and chances are
you will lose that $200 more often than not.
You just told him to go on a portfolio suicide mission by even considering going on the high leverage.
First and foremost, leverage trading is not even a thing anyone with less trading knowledge should be considering in the first place and secondly, if you are trying to trade the highest leverage, you just set yourself on the path of liquidating very fast in the case where things end up not going right in your favor, which I am sure it would not even take much time before it happens.
There is no fast way to make money, and anyone looking for it, will always at the end get into more debt. My advice is that he finds other thing to do, pay up whatever he owes and have patience with the market.