Do you have insurance?
Then IF someone takes it to the level where they would damage/steal/vandalize your equipment, then you'd have a way to deal with that.
If they already know you're an LCO, then I can't see it making a huge difference if you've got lettering or not. If "they're out to get you", it's not going to matter either way.
I see a TON of LCOs around here with zero markings on anything. I know it's not right, but I automatically think illigit, non-tax-paying, loballing fly-by-nighter. And I know that is not the case with them all.
But I can't understand WHY anyone would not want a logo and lettering on their truck. It's advertisement. Thousands of people see your vehicle each week. Why not take advantage of that?
In addition, I just think it looks much more professional to have markings on the truck and trailer. JMO.
But yeah, I think you might be a little paraniod.