Hello Nathan,
Yes you can have bikes on the back of the car and tow, BUT there are some things you should be aware of.
First of all, if any of the bike rake takes its support from the tow bar or hitch, then you have account for the load it imparts on the tow bar and make sure you don't exceed the towbar's load limits when you hitch the caravan.
Secondly, you must also be aware that having the bikes on the rear of the tow vehicle, they may impede the caravans turning circle.
Thirdly, and especially when running without the caravan, make sure your cars numberplate and driving road lights are fully visible, otherwise you will need to get a numberplate and lights board.