Well they flew to Myrtle Beach with passengers before. It was a private thing and I don't know exact details.
It's harder to fly those distances in the summer because of the warm air. It's something that you wouldn't really think of being an issue, but the only time Porter can fly to Halifax direct with a significant load is in the winter. So I don't know how things would go with a flight to Myrtle Beach in the Spring, but in the winter it shouldn't have a problem.
Two issues do come up though: space and weight. First, the back of the planes aren't big enough to fit a lot of bags. They might fit anywhere from 80-100 bags. When you have 70 people flying to Halifax, you might be looking at around that many bags or more easily. So you run the risk of bags not making flights, which in mass amounts is a logistical and costly nightmare. Simply put, you can't just say "well the bag won't be on this plane, but we'll put it on the next one" because the next plane probably will have the same issue, so you'd be perpetually bumping bags. The same goes for weight issues. Usually the planes can be roughly 60,000lbs including fuel, bags, people, crew, galleys and the physical aircraft and have the ability to take off. It depends on runway conditions, so this number can vary from 58,000 to 62,000lbs. I don't recall how much the plane physically weighs, but I think it is around 38,000lbs. Add fuel and people and you're leaving yourself with not a lot of room for bags.
I also don't know anything about profitability on these types of routes. It's true that 20-25 people is enough to break even on legs to Ottawa and Montreal, but that number goes up for Newark because of increased taxi time. I also don't know how much fuel costs.
