I know alot of guys that get into this business that just dont pay tax on anything they collect in cash. That's fine and great until something happens one day. You should be legit asap. What happens if you mess something up on a site? What happens if you are driving your personal truck and have signs on the side that says "ABC Landscaping" and you get into an accident that may not even be your fault? Your insurance has the ability to then drop you and not pay any claims. Then you get sued. Then what? Then they find out you don't pay taxes either.
It's a bad idea!