Many thanks for this.
Our camping trip went really well. The roof bars (though ridiculously expensive) were at least fitted at the Seat dealership and then we hired a roof box for a week. We didn't open the panoramic roof while the bars were fitted/box was attached but I'm curious to know if this would be OK.
Even with its black alloy wheels (well, we are in Essex!) our car certainly didn't look very cool but at least we were able to take all our stuff along and we have camped in luxury for a week!
The very expensive roof box on the Seat website is out of stock and there are none in the UK until later this month, so we hired a Autoplas 450 box and have just bought one in black, to match the car (for only £75 or so plus an extra £20 for the extra wide fittings (because the bars are wide), with the place we hired from generously deducting the cost of a week's hire, so that was really good in these credit crunch times. Can't get excited about roof boxes and although the fittings for our new one are pretty basic, we are only intending to use it once of twice a year. Even the expensive ones look ugly!
There was an annoying whistle (we think from the bars) but this stopped when the box was stuffed full of camping gear. Weight limit for the box is 50Kg (so under the
Ibiza weight limit of 75, even with the weight of the box and the bars, I think) but lightweight bulky items were all we used it for and that left plenty of room for heavier stuff inside the car.
Would definitely recommend. Fuel ecomony was lower, as expected, but we were still getting 50+ mpg.