I have a good friend who has hired guides at both Hartwell and the Hill. One of the problems he experienced is that since neither lake has a size limit, once each person catches their 10 fish limit, the day is over. In his case, this was before 9:00 AM each day, and they never caught a fish over 16 inches long.
I think it would not be too difficult in March/April to catch 10 fish on either lake. You might want to explore this with any potential guides, BEFORE booking the trip.
Steve Crenshaw and Stan Bagwell are both great guides. You don't have to keep the fish so don't worry about reaching a limit. Just fish until you run out of bait! Crenshaw is listed in the link aboove by Tarpoon. I do not have Stan's information.