5 speed vintage bike on Zwift Hub One

If the frame is steel you can probably do this. The Zwift Hub will probably be about 10mm wider than the frame. To make the alteration properly you would bend each chainstay 5mm (assuming it’s already aligned correctly before you start) and then align the rear dropouts so they remain flat against the axle without flexing them. If you don’t care about the frame then go for it. I doubt you’ll hurt the trainer.