Thinking if a Thule bike rack will solve the issue of my sons BMX been a little too large for the rear storage in the caravan whilst towing

Looking into the Thule bike racks for my roof rails, wondering which model is required?

For 1 or 2 bikes

I've used the ProRide 591 without problems. I've now switched to the 931 tow bar carrier - much more convenient with the increased height of the FL2 over previous car, and no more height restrictions.