From my perspective, build one first and be happy with it before mass producing. Cut your tube long enough for the lights + what ever distance the top part of the inspection T piece is. My first one I had strip at 2500mm and cut the tube at 2550. Missed the first few pixels as they were hidden in the top of the T piece. Fixed that for the remainder by cutting the tube at (I think) 2650mm (cut longer then you need and trim after). I went with the smaller tube, which meant I had to use the smaller T piece. issue with that was I was not able to push the pigtail out the back of the T piece in one piece, so I had to cut and solder each one.
Only other thing is definitely brace them. I didn't and they were just all over the place (as you can see here View: https://youtu.be/E3P5hSarBEY?t=10m41s
Last thing I found it difficult to measure and cut with the tube bent. I would have *tried* to get the tube straight (leave it out for a few days flat in the sun?).
+1 on build 1 first to ensure its right for what you need.
Mine used 2.5m of strip, but the air seeder hose/tube was cut at 2.6m so that the lights were above the T-piece joins for the feet.
I did not use a brace and just used tent pegs through the feet to hold them in place - they didn't move all Dec. Most of my weather comes from the West which is the house direction, so my lawn is slightly protected, but build to meet your own conditions.
More info on mine here: View: https://youtu.be/Cd0-0sAJ-pE?t=33s
I ended up cutting some short 1cm pieces of some 15mm PVC pipe I had. Then pushed it inside the air seeder hose at each end. This presses against the pigtail tightly and keeps the pixel strip tight and against the inside of the arch of the air seeder tube. No hot spots, looks really good.