[jakobnev]

How long is this hill?

If it's short enough, then the "semi"-approach of gaining a bit of extra speed before the hill and losing some up the slope and to gain it back after the hill, might be best. (all in fifth)

For a longer hill, alternating between 4th and 5th might be meaningfull.

An interesting experiment might be to pulse in 3rd and lose speed in 5th. (allthough you might feel you are going too far with the hyper-miling)