I had a 29g with a Coralife 65x2 PC and a Carbo-Plus Co2 doser from 2003-2005. I took a somewhat "organic" approach to the tank and had pretty good success. I simply added plants that I liked until it looked the way I wanted it to look. I have no clue how much Co2 was being produced by the Carbo Plus unit but I didn't have horrible algae problems. I did not consider the light to be excessive and at the time, the 3-5 wpg rule was still followed somewhat.
Actually, the light fixture is the only thing remaining from that setup and I'm going to use it again on a 36 bow. This time I'm using pressurized Co2, however. At this point in the hobby, the US has played enough catchup with Europe and Asia in regards to pressurized systems and regulators are not nearly as expensive and judging by the forum, a lot of people have worked hard at removing the guesswork that would have been involved 10 years ago.
If your fixture is like mine, you can run one bulb at a time. I would try different photoperiods until you come up with something that works for you. It's worth a shot. If you need DIY Co2 or pressurized, I'm sure there's a system that will cover your needs.