Suitability of Giant Aero RS2 for occaisonal on-road mountain trips
If you're going on road, a hybrid should be fine (like the Aero RS2) - the gearing and tire size and handling should be reasonable provided you don't go too high on the weight. I'd probably not load it too much though (for that you want something intended for touring). At 30 kg of stuff though, I think I'd look for something more touring bike-y than the Aero RS2 - its part of Giant's casual series and carrying 30 kg of stuff isn't really in the casual realm and you could likely do better for 900 euros in that realm. 

A more reasonable option overall would be to buy a bike that works well outside the week of mountain touring, and rent a bike for the week long mountain trip.