Liquid rubber

Yes, you read that correctly. I've read that a few people have had a challenge when a stone gets trapped in wheel tread and then ejects itself upwards at a rate of knots into the underside of the wheel arches. With unpleasant consequences as the stone hits the glass fibre and can cause an impact star in the fibreglass or pushes up enough to cause paint to crack.

AK put in a very thick cloth in the undersides as shown in these photos to negate this but it needs painting to get it looking uniform and professional. 

At the same time the engine bay needs a good coating too to stop any reflections in the stainless cladding being anything other than black! It's a pain but better to do now than later as it's more of a pain once the body is on and engine in. (Thanks for that tip Tommy)

Front wheel arch view to headlamp hole.

Using a roller will get a good finish as I'm not worried about going the whole hog with a schutz gun on an air line.

So using this stuff, liquid rubber which is used for sealing flat roofs is a good option.

It creates a waterproof seal with rubber, so two coats will hopefully add some additional shock resistance too.

It's what I imagine trying to paint with bitumen must feel like - hard work.

Photos of finished result to follow.