Dennis, did you come to a conclusion?
I have an odd-shaped five gallon that is a couple of inches shorter in length than the 5.5 gallon. I use the 1 x 13w bright kit and have been able to grow low-light and light-demanding plants such as glosso without any problem. I have the light sitting approximately 1/2" above the glass. I'm not sure how high I would need to raise it to get good coverage on a 5.5 gallon, but I can check into it and let you know. Since you are planning on going the low-light route, I would think raising the 1x13w would be a good option. However, I'm not sure what that would do to your idea about having hair grass in the corner of the tank.
I have an odd-shaped five gallon that is a couple of inches shorter in length than the 5.5 gallon. I use the 1 x 13w bright kit and have been able to grow low-light and light-demanding plants such as glosso without any problem. I have the light sitting approximately 1/2" above the glass. I'm not sure how high I would need to raise it to get good coverage on a 5.5 gallon, but I can check into it and let you know. Since you are planning on going the low-light route, I would think raising the 1x13w would be a good option. However, I'm not sure what that would do to your idea about having hair grass in the corner of the tank.