Of course, this would probably require permission from the HOA.  

Note....I never gave them permission to post my deals....but the exposure has been good so I let them keep doing it. 

The tenant sent a letter today accusing me of trespassing on the property for not asking permission to enter.

You are likely to cause much more hurt and bad feelings (and therefore damage to the business relationship) by asking permission.

Things like permission to send emails, fliers, newsletters, to call again, to add them to some other value added thing you do.

What if they don't own the place or the rights to the place and they just take my money and run (and the landlord comes and says that I can't live there because they never gave them permission to rent it out)?

Of course a mortgage company is not going to grant you permission to move it to an LLC or trust but why would you ask in the first place?

Tenant has called a/c repair companies to come out, but no one will without either the property manager or owner's permission (Owner on title is a Land Trust, so no way to find out the individual).The living conditions are becoming uninhabitable.  

In that case, tell the seller what you're doing and get permission to show - usually once a week.

Assuming you have gone through that permission seeking, you could do this.My next point would be - WHY WOULD YOU SELF MANAGE?