If you put them inside the caravan, they only get in the way when you arrive onsite and are trying to set up, also you risk damaging the inside of your caravan with them.
I then started to look at bike racks, if you use a hatch or boot mounted rack this hinders you as you have limited access into the boot.
Best option was on the roof, up out the way and you can keep them there when not in use.
You don't get any extra turbulence that I have noticed unless on a very windy day you can feel them slightly getting caught in a cross wind. but what you do get is 3 to 4 mpg less.
It does help spread the load. If you have a full car, heavy nose weight and bikes hanging on your tailgate you are likely to be over the rear axle max. On the roof shares the load over both axles.
The other reason I like it is they can't get hit by another car. I have had a toe bar mounted rack but got rear ended with it on. Bill was huge, new toe bar, cycle rack and 4 new bikes plus the damage to the car itself.
Never noticed any difference when towing with 2 bikes on the car roof, just remember the car also has a maximum roof load, never noticed any increase in mpg also.
Used to carry bikes on top, but as we had an MPV it was getting a struggle to put them on. Final straw was when I lost balance a bit and nearly dropped bike onto car roof.
We now have a MaxxRaxx which mounts on the tow bar but allows you to fold it down to gain access to the boot, without removing the bikes.
------------- Alan
2016
February C&CC Theobalds Park
March C&CC Salisbury
May C&CC Adgestone IOW
July Le Clos Auroy, Auvergne France
August C&CC Polstead
August C&CC Oxford
October C&CC Lauder
Yup there good but not so good when your towing your caravan.
There is also some fancy roof mounted rack that folds down for easy access. Can't remember the name of it though.
If you put bikes on your tailgate when towing you adding additional weight where you least need it. Depending on type and number of bikes you also need to watch they don't hit the caravan if making a sharp turn.
Appreciate the point about the weight on the tow bar, but the Maxxraxx comes with an extension to heighten the rack to keep clear of the jockey wheel handle. Although yes, tight corners can be a worry, but the long A frame on my Adria mitigates that.
------------- Alan
2016
February C&CC Theobalds Park
March C&CC Salisbury
May C&CC Adgestone IOW
July Le Clos Auroy, Auvergne France
August C&CC Polstead
August C&CC Oxford
October C&CC Lauder
We have bikes on the roof of the car, and also carry a small three step aluminium step ladder, only a few kg, in order to get the bikes on and off the car. It balances the car better. Also two bikes on the a-frame of the Adria, but we have to put the caravan spare wheel in the boot of the car to reduce the nose weight to a realistic level.