Exhaust emissions (Volvo xc60) marking caravan

IanTG

just returned from our first long (ie more than a weekend break) caravan trip covering 1800 miles and the lower half of the front of caravan has lots of little black flecks on it. At first, thought they were flies, especially as we had travelled abroad,
but I now think they are exhaust emissions. They do come off with effort, but wondered:

1. Has anyone fitted a deflector to exhaust pipes to deflect fumes downwards, as on xc60 they are horizontal pipes?

2. What is best cleaner to remove flecks?