Hi, thanks for your question. My name isXXXXX can assist with this.
Is the right of way for the passage of vehicles, people, or both?
You have the right to prevent him from doing anything that would interference with the use of the right of way. Obviously, the painting of lines does not, of itself, amount to a physical interference, but what it does do, is encourage people to park there and thus, interfere physically with the exercise of the right of way.
Therefore you should be able to take action now because what you have is an adjoining owner encouraging the obstruction of the right of way over which you exercise your rights.
I would like to think that this is something that should be resolved easily following a letter being sent to the business park owner outlining your position, and that as a consequence, he would not continue in this way.
Needless to say, if vehicles do block the right of way, with the business park owner's consent and encouragement, then this should be actionable against him.