I’m looking for a service that tenants can pay their rent online / auto payments.

If it is not legal, it will not scale.

I’ll definitely look into what I can and can’t work on legally

This tenant is month to month and can be given 60 days notice to leave so we receive it vacant (double checked to make sure and it's legal).

We're letting her stay here for a couple of days and going to follow up on the legalities of her staying till she's 18 tomorrow, I don't want to put myself in any bind there. 

These are often transferred in bulk... with the deed having page after page of legal descriptions and possibly a chart of annual rents.It should be easy to find people who own hundreds of ground rents by limited research or just asking around.Each ground rent gets registered with SDAT using their form.You don't foreclose a lease... you pursue an ejectment action or action for possession.

Disclaimer: Always check your local laws and regulations.That said, if the tenant does not move at the end of the month, you will probably have to initiate legal eviction proceedings. 

I keep reading and can not figure out a clear solution that keeps me covered legally.

They have you send in pictures and they throw it up online.

You hope not, but there is always the possibility of a bad tenant that could cost you a lot of money in lost rent, legal fees and damage.