I'm a dealer, and I'm a couple hours away from Myrtle Beach (and the east coast beaches down to Savannah).
I frequently get asked about pinballs for beach houses, airbnb, etc.
I recommend that you don't put a pinball in these rental properties.
We have a 60-in-one that we ridiculously overbuild, that survives what your clients will do to a machine. (Tempered glass over the LCD screen, overbuilt internals with double brackets to support 250lb people climbing on the game, etc...)
That's a suitable piece for a rental property. It survives what your clients will do to the game.
I currently am working with a guy who put five pinballs in properties at the beach. All five are in extremely poor repair, and he can't find someone to 'shop' the machines locally, so he's in conversation about bringing me machines, and having me 'shop' them, even though I'm 3 hours away.
On unlimited free play, with a set of customers new to the game every few days or week or so, you'll get a ridiculous amount of wear and tear.
Now, pinballs are designed for commercial operation, to be in taverns and bars and soda shops and arcades, and to be in service 24/7. But in practice they don't get more than a hundred plays a week, rarely, extremely rarely two hundred plays a week, even at top earnings places. Certainly it's rare to get more than that level of play once a machine isn't the newest game in the room. (I'm willing to be corrected on this if it isn't true...)
Your pinballs on free play could easily get twice that wear and tear.
Pinballs break. They break a lot. Usually they break in simple, easy to fix ways. Frequently they need specialty or hard to obtain parts. Rarely, but often enough that you should take note, they require an experienced pinball technician to fix.
In your situation, every time you have a pinball problem your clients will have a less-than-perfect experience. They'll downgrade your online ratings, they'll ask for money off of what you charge them because they didn't get the full experience promised... Every time the game is broken it's a customer relations problem.
So, if you are convinced you need to do this, find an operator of pinballs. Someone who has the staff who fixes the games in bars and taverns at 11:00 at night on a Friday night. Someone who has technicians on call seven days a week.
Getting your customer's pinball service problems fixed promptly is a distant second to not having problems, but it might save you a couple of poor reviews.
Have a technician on-call.
You don't want your customers mentioning in their reviews that your pinball was broken.
Back to 'shopping' your pinballs. You can patch things on the route for quite a while, but eventually you'll need the whole machine overhauled. This will happen much quicker than you'd think when your pinballs are in extremely heavy play environments.
Make sure you have a plan to get your pinball out of the rental property and delivered to a pinball 'shop' where the machine can periodically be refurbished to like-new status... or at least 'not going to immediately break again and again' status.
In St. Louis where we had a very large pinball route, machines would rarely be 'on the route' more than 3 years before they were pulled in and gone through. 'Shopped'. Since you are likely looking at double the wear and tear, consider that you might need to 'shop' the game every 2 years.
I've done 'shopping' a pinball at location. It requires an extremely good technician, with a ton of parts to get it done in a single trip. You could do this yourself, but don't underestimate how much stuff can get broken and worn out in a year of extremely high usage. It's a lot of work.
You have better results if you 'shop' a pinball at a pinball 'shop'. Where you have time, parts, and tools to fix things right instead of fixing things 'for now'.
Finally, yes, near the beach you have mold problems. You have corrosion problems. You have salt air that causes the machines to pretty quickly lose that 'new machine' luster as the metals react to the salt.
But in general, the machines hold up pretty well.
So, to sum up.
Ask yourself 'how am I going to get 100% uptime on my pinballs'?
They'll need to work for every customer, every time.
You'll need to spot check the machines after every guest... or deal with poor reviews of your property.
I tell people all the time:
"People LOVE Pinballs. The reason you don't see them everywhere is not because people don't want to play pinballs, it's because they are broken all the time. Pinball isn't much fun when it's not working."
I mean, do what you like... but the juice isn't worth the squeeze on this one.