I wouldn't give up an inch of your space. If they want service, it's just tough luck and they have to landscape again.
I used to install gas lines on residential properties. We would do what we could to please the clients, maybe run an extra few feet here and there to avoid disturbing their landscapping, but sometimes you just have to do what you have to do... But that shouldn't include going in and affecting someone elses property who isn't benefiting in any way.
