Hi sorry, I don't surf this forum alot. I know that T6 exist, but have only heard about it once. So I was hoping some one who knows better might jump in.
Anyway, good reflectors will help, but it's not going to be anywhere near what you can get if you double the wattage or just even having an extra 35watt tub in there.
I used to be under wattage too. From my experience, I tried replacing my standard aquarium light bulb with a plant specific light bulb. My plant got a bit better but it was not enough. I replace my white reflector and added Mylar to 3 sides of the tank. It got a bit better, but still not enough. In the end, I have to replace the canopy and put two sets of light which doubles the wattage, and only then did I get my plant to not just grow but flourish as well.
So, I think your option is to ditch the canopy if it can only accommodate one strip of light. Buy an aquarium glass top that fits your tank top. Then put the light strip on top of the glass. You can raise it a bit if you have heating concerns. Then go out and get another light strip and put both on top. Then you can turn the CO2 back on and sit back and enjoy the plant exploding in your tank.
Err ... actually, most people have to battle algae at this point, but if you add your fertilizer dosage correctly, you might not have to.
A second option is to make your own canopy that fits 2 light strips.
A third option is to buy an egg cart? (One of those plastic square grid that is used to diffuse light in the office buildings). Stick that on top of the tank to prevent fish from jumping out, and hang your two light strips over the tank. If you have super high ceilings, buy a portable cloth hanger (similar to the ones the bell boys push around at expensive hotels). Put that over you tank and hang your light.
If all these are too expensive for you. Then you might want to stash the CO2 kit or sell it and just concentrate on low light plants. Things like java moss, java fern and maybe even anubias or crypt might stand a chance at such a low light. But even if they survive, it'll grow at a super slow rate and may never be as vibrant and a CO2 injected tank.