If you go with a 4 bike rack ensure the bike rack has sufficient weight carrying ability.
The max ball weight on the Craptiva is 200kg and the Outback was 180kg and the bike rack was 80kg max weight of bikes.
If you've got 4 good bikes then it's fine but if they are k-mart specials then they are likely to be heavy dungers.
My 2007 full suspension x-country bike was cutting edge in it's day & weighs 16kg with pump/tools, underseat carrier, etc. My daughters Merida is 17kg & the other 2 bikes are big, cheap porkers.