Quote from @Chris Lo: Which platforms/websites do landlords use to find the rent rate, how long the rental properties have been on the market, and all the details about other rental properties?

Listing on multiple platforms does affect ranking by platforms but not as much as you think.  

What if something changes with how that platform works?

Has anyone bought from the platform?

Once withdrawn from the platform, owner is free to sell the property.

Fractional Ownership: Small Steps, Big ImpactNew platforms now enable fractional ownership of high-end properties.

@Rene Hosman, I'm firmly in the online platform camp for preference.

I agree that DealCheck (or the BP calculator) does not provide enough tools or functionality to analyze those types of transactions (yet).But I would argue that it does a great job at analyzing more traditional buy & hold SFRs and multi-families, as well as flips and rehab projects. 

These platforms include RentRedi, Stessa, Avail, Innago, Apartments.com (formerly Cozy), and TenantCloud.Pretty much every platform mentioned contains the features you are going to need.

I know Shopify typically is a more commerce base platform.