Happy Birthday to wildfire and Gr8bear 
Have a great day and I hope that you can get a ride in 
                                

Overnighting

Other than, using a directional tyre in the wrong direction will possibly:

• Result in an unroadworthy vehicle, and leave the driver exposed to a penalty from VicPol (as happened to a mate).
• Void the vehicle insurance - in the event of a crash and a sharp assessor or VicPol noticing (and perhaps another penalty).

This would be a problem with EV and ICE (with directional tyres).

My comment "short term" was meant to mean that you could probably use it to get your vehicle to a tyre service or garage etc to have the damaged tyre repaired or replaced.

Bit of a grey area I guess but I would certainly use one in an emergency.

Did you know it's okay to use a space saver tyre in an emergency yet using different size wheels and tyres on the same axle is actually illegal?

You might also be interested to know that there's actually no mention whatsoever of unidirectional tyres in either the Vicroads Vehicle Standards Information - Roadworthy Requirements info sheet or their Tyre Maintenance & Repair sheet... 

And finally, if running unidirectional tyres in the wrong direction is illegal then surely you'd have to carry 2 spares?