Software to manage multiple properties and businesses?

[Nate Martin]

I was having lunch with a very savvy real estate investor who has so many balls in the air it was incredible. 

From what I gathered from our conversation he has over 20 rental doors, multiple air B&B's, he runs his own window installing business that is continuing to grow, and just bought land and is going to be breaking ground on a new multi family property. 

Not only that, he owns a 2 laundromats, and a car wash and is looking to expand into storage units in 2021.

Here is where it gets crazy for me, he told me that his wife does all the paperwork... and they do everything old school. Stamps and letters style. He says she gets mad at him when he buys more stuff because that only means more paperwork for her to manage and keep track of. 

I want to be of service to them, they are clearly running a great operation, and I understand if they have a system that works for them I don't want to get in the way of their method, but he said that the cost of stamps are killer.  I figure I could help them transition into the 21st century and take some things off their plate so they aren't up to their eye balls in paperwork. They don't fear technology or anything, I just think they managed to scale without getting the proper systems in place until after it was too late. 

So fellow bigger pocketers, what type of software do you guys use to manage multiple projects, to make sure all your bills are paid on time, to make sure all your contractors are paid on time, and make sure that you get rent collected when it needs to be? I'd like to offer them anything just so his wife see's him buying more things as a good thing instead of a bad thing, so they can focus on spending time together as a family and not so much time worrying about their business. 

Any insight on what software you could recommend would be great! Thank you so much!