Hi Richard i have a number of years training under ipaf and pasma ... the biggest problem it would seem that you are going to have is how to safely carry out the maintenance on the roof of the vehicles ... exiting any thing from height will require a very thorough ra and is not recommended by any training body. The use of harness could be an idea, but again a suitable anchorage point or points would have to be in place. Another item a lot of people seem to overlook is the need for a rescue plan, part of the WAHR. Some transport companys operate an advanced tower scaffolding system used to access various parts of the machinery. These can be folded down and transported to and from site in a van. For more information you could consider speaking to pasma or a similar organisation. Hope this has been of some help. Regards Andy

Thanks for the advice and assistance Gentlemen.