What Google allows
One listing per location, and a location means a place with your staff at it during the hours you say you're open. A mailbox rented in the next town isn't one. Neither is a friend's garage, a co-working desk you don't sit at, or an address you pay for and never visit.
On the listing you do have, there's a service area setting where you name the towns you drive to. That's the built-in answer to the question, and it's the one Google intends you to use.
What happens when somebody tries it anyway
Fake locations are one of the things Google's spam team works on hardest, because they're the most common abuse of the map. A listing at an address you can't verify gets suspended, and the suspension can land on your real listing as well.
That's the whole risk in one sentence: a listing that was working, gone, while you appeal. It's a bad trade for a listing that was never going to hold.
What the service area setting does
It tells Google, and a person reading your listing, which towns you'll drive to. Put your real range in it and keep it honest. A service area covering half the state on a two-truck company doesn't help anything.
Don't expect the setting itself to move you up. A controlled test found no ranking change from editing it, so it's there to describe the business rather than to promote it. The thing that gets you shown in a town is a page about the work you do there.
The part that does the work instead
Each town has its own list, and Google fills it from businesses whose own website says, in plain words, that they work there. One listing plus one real page per job per town is the shape that covers a whole footprint without breaking a rule.
It's also less to keep straight. One phone number, one set of hours, one place to answer reviews, and a set of pages a person can read. When the number changes you change it once. When you add a town you add a page, and nothing on the listing has to move for it.