Mike, but as said, i had my car on the road with no whaletail for near on 2 years, and i did several track days with the car in this way.
from a personal point of view i had no troubles or issues with it.
and as you already know, i also have a spare tailgate which is complete with both spoilers
and how can we take anything Adam says as serious, he drives a saxo as a daily car with a Peco Exhaust hanging out the bag, reving around Tesco car parks!! lol, sorry Ad.