One thing I’d change. Rather than using couplings on the four legs, heat the pipe and let it custom mold onto the vacuum mounts. PVC when heated becomes like rubber until it cools, so you can even stretch it.
A 1200 watt heat gun will work. It’s can also exceed the melt and start scorching it. A torch quickly exceeds the scorch temp. You want about 220 degrees. Boiling water is enough to bend and mold PVC, but it’s so close to the lower temp, that as soon as the boiled PVC touches anything cooler, it becomes rigid again. So boil water is great for bending PVC only.
