I've seen several threads regarding how to power the Teensy 3.5 and noticed the recent updates to the assembly manual that get to a workable solution.
Has anyone tried to cut the pad on the back of the teensy to disable the PC supplied 5V and power it directly from the 5V supply? CAUTION: If you try this without cutting the pad, would could fry your computer's usb port which might be the reason why this is not in the manual...
Has anyone tried using level shifters to boost/step down the 3.3V pins on the teensy to 5V for the encoder/switches? This would also let you use the teensy 4.1 which is not 5V compliant, but 5 times faster than the 3.5. These have worked great for me in the past with 3.3v teensy boards https://www.adafruit.com/product/757
here is a link on how to disable 5V power from pc on a teensy https://www.pjrc.com/teensy/external_power.html