The landlord charges them a flat $1k a month in utilities along with $200 a month for lawn maintenance. 

It's purely a flat fee membership model.

He charges a flat fee for tax prep and no fee for any questions that may arise.

I hav some excess cash that I would like to put in a rental property.

Since your tight on funds and need to sell fast, I recommend a Flat Fee Listing Brokerage that accepts a flat fee to be your Listing Agent. 

From there we aim to identify the best possible fit with a tax advisor in our network and then get started on a flat fee basis for that process.

A tenant who wants to stay and is on a fixed income is likely to stay a long time which means you won't have excess loss to vacancy/turnover.

It’s not going to be high volume that wholesaling implies.If you’re familiar with the real estate economic cycle, you’ll recall that the period following a rapid period of price inflation leads to a flat period (stagflation - rising interest and flattening sales). 

In my area the water company will forgive excess usage if it can verify there was a temporary water leak causing it. 

I do have two buildings that the water is on a flat rate fee.