Its an interesting conundrum. Id say in the UK, fear of theft etc would deter companies from prominent 'yards'. Everywhere I worked when in the UK was hidden in an industrial area, or down a farm track, never outward facing signage. Here in Canada, theft is not an issue, but you never see big roadside advertising for tree firms, I do wonder if it would be helpfull though, put the company name in peoples heads. Truck signage however is very effective in my mind. I wouldnt know how France differs, Id be tempted to give it a go for a year maybe 2 and see, its only a lock up, not hard to move into and out of.