If you do insist on using a bra, make sure you clean/wax the area where the bra touches your car before putting the bra on. Also use painter's tape to cover the areas where the bra will potentially flap or rub.
Bras help with preventing chips, but they can also scratch your paint if not used correctly.
For a 1 off trip, I would just use a couple rolls of blue painter's tape and tape off the front end. It might look ghetto, but it's just 1 trip and a cheap, non-permanent solution.
