We bought an Adria Twin 600 SP last year and have struggled to find advice on tyre pressures. The only information on the vehicle door sticker, and in the vehicle data says 5.5 bar (80psi) front and back, which is fine for winter storage but far too high for use. I eventually emailed Continental tyres and got a very useful and comprehensive response with a table of axles loads against pressures for front and rear axles for my particular tyres. The table is attached.
I hope this may be of use to others.