The 8th Avenue side is typically the side to find Redcaps, as that's Amtrak's side of the station. I believe that there is even a phone/intercom over there with which to call for a Redcap, won't swear to that. The issue is that you could be told to go around to the 7th Avenue side to actually meet the Redcap because as I noted at that hour Redcaps are sparse.

A second issue that I see is that you're not going to be allowed to stop for very long, if at all, on either the 7th or 8th Avenue sides. They are largely given over to Taxi stands and the cabs are often lined up along the length of the block which would block you from pulling to the curb.

But even if you can pull to the curb long enough to drop her off, I would not count on being allowed to remain stopped there until a Redcap shows up. It's quickly likely that you'll be chased off once you've unloaded her and the bags.