Update
I was able to return the car to the airport just fine. The HLE assured me that I would be charged the same rate whether I returned it there or to the airport. At the airport, when the guy w/ the express checkout scanner (or whatever it is called) did the checkout in the parking lot, it gave me the rate of $195. But when I went to the desk inside, the lady was able to adjust it to $46. ^
So I suppose this depends on the area. If anyone is considering doing something like this, I recommend calling the location beforehand and making sure.