We tow an Avondale Landranger with a Vauxhall Monterey long wheelbase (Rebadged Isuzu Trooper) We carry up to 4 bikes on a Witter 4x4 towbar bike rack. The bike rack is angled-out around the rear spare wheel. It is easily fitted and removed for opening the tail door. This arrangement is fine on the open road but we tend to take the bikes if making sharp parking manoeuvres as the bikes can, then, catch on the front of the caravan. We take out the jockey wheel for the same reason - we did once buckle a bike wheel on the jockey wheel post when making a sharp turn onto a pitch in reverse!! The bikes and rack, also, rather obstruct hitching and unhitching but we fee this inconvenience is outweighed by having the caravan interior clear for stops en-route.
We previously carried the bikes vertically on Paddy Hopkirk cycle racks fastened to the roof rack - but that was a stretch to put them on- even on a, much lower. Peugeot estate car.
We have travelled extensively over 7+ years on the Continent and in the UK with both types of rack and few problems.
Incidentally we, also, carry a lighting/number plate board so that we can carry the bikes on the car when we are not towing the van.