I did it at 40° in a self built 'Keetel'. Lights were (there were no LEDs yet available ca.20 years ago, so i used 3x 600W HDIs) vertically hung. It was a big thing in NL that days. Tremendous yields! Plants loved growing in a 40°direction. Bigger yield in less space! You can grow in layers then.
I think 0° / horicontal growing will mean too much energy for stabilsation of the stems. I think something round 45° is better.
Take a look at the construction of a 'grow keetel', you might get some inspiration if you are still interested in that topic...🖖