Compliance items such as adding smoke detectors, hand rails, fire resistant garage entry-door and new stairs outside.

BTW - AirBNB is a platform where you list your Short Term Rental.

In my area (near the beach) its mostly families and they want cabanas, baby items, chairs, coolers etc that we do not provide but I have a local vendor that delivers and picks up these items and charges a few dollars per day for each item, and give me a 20% referral. 

are there any other platforms for such listing? 

$540 is not unreasonable for a home of that size and the items you mention.

Like you, when I'm working with clients I highlight the key advantages of the conventional rehab loans (Fannie Mae's Homestyle and Freddie Mac's CHOICERenovation) are:- They can be used for investment properties- You can include luxury items- They have a higher limit – $806,500 in most places.Jeff

At the end i will add a list of items why adding a single ADU in single family zoned areas may not be the best RE option.The most common value add is via a rehab.  

Then we review the submitted file items and come back with questions or ask for additional documents it is a normal process.

Also, what others have said, the personal touches on what is in your place (e.g. providing all the essentials instead of having people buy TP, coffee, shampoo, etc.) and the quality of those items (no tattered towels, stained sheets, etc.).  

Some of my personal friends are on the list, and I highly respect them as my peers.