Not a five gallon, but I'm just seconding the way labloverl divided their tank. When I first divided my ten, I bought the ten gallon divider from petsmart. Yeah...it was fine when I went to bed, but when I woke up both fish were on the same half of the tank, and the new veiltail had badly injured my old delta, Jazz. When I used the black craft mesh and report holders, it worked wonders and looked SO much better. I've had it set up that way for a while now (different fish now though, I lost Jazz :'( ). I've done guppies | Male betta, Male betta | male betta, nothing | Male betta, and currently Female betta (soon to add some female guppies) | Male betta. Just a note; female guppies are always having babies, and the babies get through the divider. So don't count on it to separate babies from adults if you have livebearers.
Only suggestions I would make, my Rory bubblenests like a fool because he can see Sexy, the female, on the other side. Some people I've seen put two dividers, with a small section in the center for heater and filter. I've never had problems with aggression from any males, Rory is the first I've seen that he even notices another fish on the other side. There is a protein buildup on the side with the male (the female's side has a baffled filter) but otherwise, the divider works amazingly, and looks great.