Fitting a Thule V16 Bike rack to MH

Tinny20

Does anyone have any experience of fitting a bike rack to their MH please? I can't find a dealer or service provider that can help. I'm happy to fit it myself but very wary about drilling into the back of my brand new Itineo. When I tap the inner rear wall it sounds solid towards the top and hollow slightly further down. I don't know the composition nor can I obtain any technical data from Rapido/Itineo. Any help/advice would be appreciated.