Put a small logo on the doors, no number! And put something on the door to the chip box, no number! I am not a big fan of having phone #'s on the truck. Word of mouth is best.
You can also put you name across the top of the truck above the cab.
I wouldn't take the time to hunt down a company that didn't have their name and number on their trucks. I get great leads doing work in gated communities with clean trucks with phone numbers on them. I think the logo is just right, I see a lot of trucks around that are so busy that you can't take it all in. Name, logo, phone #, website, is about it for us, although the previous owner did put "Licensed and insured for your protection" at the bottom. I could do without it, but it was already there.