3" or even 10" is still too close, especially 3" will be detrimental to the coverage and spectral blending/color saturation. Try looking at your hand at arms length and then move it towards you eye, and then notice how much it affects and reduces the percentage of your peripheral vision in relation to the distance as u mover your hand towards you. Now imagine the a leaf in relation to the light source, yr panel, and it will give u an idea of how much coverage u have left. U also have to remember how effective the leaf is on absorbing light, especially that's what it's design for. Remember sunlight, which is constant at any distance, can only penetrate very little into the canopy as even outdoor lower buds under the canopy are severely affected as demonstrated by it's size and density. You also have to consider unless u're running a single band spectrum like A51's all 3700k, you would need ample distance for spectral blending, because of the multi-bands. Of, course leds on average operate 15F over the ambient temp. and I've had colas touching my Blackdog 700watter before with no burning, just a little drying, but this doesn't mean it's a good idea. The cover, especially diffuser type like BML's and floro's is it will heavily effect the intensity, because that's what diffusing means, to spread/scatter the light. Even standard protect glass will reduce as much as 10-15% of the intensity, now imagine what a diffuser type like the BML's will do. This is good if you're growing low-light intense crops like lettuce, but not our light-intense girls. It makes sense because BML and Illumitex bar type design is primary design for large scale, multi-level application and are now being applied for canna-specific application. Lose the cover and the IP65 waterproof thing and u might have a winner, since the idea and flexibility of adjusting the coverage is a thumbs-up.
