What's the scenario going to be?
If it's a "Get the maguffin and get back to the boat" scenario, maybe a balanced points limit isn't necessary? Start the scenario with hybrids, then escalate to fishmen, and then a Deep One? So it's a race against time, as the ship's crew will eventually be overrun if the Lurker player can delay their escape.
And since it's a specific scenario, why go with the starting 15 points limit? Toss some skills onto the humans (I think they're each worth a point, right?).