I think you only need small logo's down the side of the ute saying the name, and because you dont want to cover the ute too much,...the big selling point will be on the back of the tray! cause thats what people will be looking directly at when everyone is drving behind you (while your hooning ahead of them all

), and then some contact numbers on the back of tray and then a website sticker for your business on the back window with contact number and name...
The ute signage will only be when your not pulling the trailer (because when you have the tralier when your working thats enough signage by its self) so say weekends and social times for you, so dont kill the ute with too much just enough in the right places
Just my thoughts anyway
