I've hacked together cables to run all three from a single psu, using all the 12v lines from all the unused sata and peripheral cables to gain the extra pcie cables it needed. I've had it running for a while at that setting without getting too hot.

I had problems with the raspberry pi not detecting all of the miners at the same time (each worked individually) and some of the other usb devices working erratically when all were connected via one hub, so I swapped that for a powered hub which improved things except still only detecting two miners, connecting the miners via a second powered hub fixed it.