Fit a pair of heavily stained Y fronts around your steering wheel!!!! nb not my own idea but just had to share it,
Have a word with @Barry Haynes as he the main supplier around these parts. Apparently he gives a good discount on multiple purchases!!
I've been using a bay steering wheel very successfully as a contraceptive when tucked down my grits. Apparently whoever had your idea thinks like me!
Stoplock for the steering wheel and wheel clamp is your best bet. Hidden tracker is a good thing too so you can find its location on Google maps and it alerts you if it the car moves Failing that I would consider leaving a protective staffordshire bull terrier in there