In this case the best way is to use socket directly, and I don't know why you want to exclude it ;-) This is not to reinvent the wheel, as you want something that no existing module delivers directly (at least to your knowledge and mine).

Any way, the easiest way is to use socket, and you don't need to waste much bandwidth. Even don't bother to use HEAD request, just send a GET request, reading the first several bytes back to get the response code, closing the socket, and going to check next link.