Otherwise, if you're assuming third party management, then maintenance is either baked into their fee or charged hourly like a vendor. 

If Tenant fails to establish a utility account, becomes delinquent, or is disconnected for any reason during the term of this Agreement, Agent shall charge Tenant for the actual cost of utility use plus a $25 Administrative Fee for each invoice processed by Agent.

Instead, they get compensated by Turnkey providers or builders with a marketing fee:“…we as the turnkey property promoter gets compensated by and only by the turnkey provider or builder that we are working with, they are essentially paying a marketing fee,” ( Link ).

I typically recommend that community for people that plan to use it personally and can justify the higher HOA costs and membership fees.

It also seems like you imply that the "fee" is somehow worth it based on this.

Have you paid their standard fee (or beat them up to lessen it further) or a premium to cut the line when updates or revisions are needed?

Advertise as you please, on any venue that will accept your line of work and be honest about who you are and how you can help homeowners, and people that don't want to deal with real estate fees.

I don’t believe a tenant can stay forever, and I can cover the extra payments and lawyer fees for up to two years for the tenant who will be harder to remove.

If it is more than one investor and pooling funds and deals then that is a completely different animal where you would file for a SEC exemption through a form D then ahve to file with each state the investors are in and have a subscription agreement and other docs drafted. 

Make sure you know what it's like to be an Agent before you spend thousands of dollars on MLS fees etc..