A question, I might need to get a roof rack for my 330d touring. It's got rails, all I want to do is strap a 60 dry bag to the roof which will hold a duvet, pillows and a tent in. I don't see the point in a roof box as it's over priced for what I need (one weekend this year...). What do I need to get? Never used a roof rack, now even sure which one to buy?