Depends on what you wish to use the fleet for. It seems to me the formation you're describing fits best for FvF battles. For planet farming either 6 longbows or 5 longbows with a harrier. For VEGA farming you can have different setups, but I've found harriers essential. For base hitting rancors and longbows.

Ya sounds like a good idea i mostly hit fleets and so i like to have a couple heavy hitters in the front to asorb any damage and protect my longbows and keep them in the fight for as long as possible