They just changed the rules here last year so that now the weight limit is 26K before you need DOT numbers. Prior to that you needed them to avoid be stopped by the MDOT, so most guys had their name on their truck right along with the numbers. Now that most don't need numbers, many don't bother lettering their trucks either.
As far as insurance here, you get asked whether or not your vehicle is being used for work by any insurance co regardless, and if you tell them no, then get into one and they clearly see you are, you will not be covered. Having your name on the side or not makes no difference.
I don't have any name on my truck and I get the stink eye from a lot of other LCO's like I am just another laid off factory worker cutting into their business.

I've been doing this longer than most of them though, so I don't let it bother me.