I am dealing with a broker that wants a pre-approval letter prior to showing me finances on a mobile home park. 

I own commercial property in Mobile, Alabama, and I am at the end of a 15-year lease with Lamar signs, who owns a digital sign on my property.

I plan to give them a call once I can track down the phone numbers.My question is, what things should I be doing to prep before I pick up the phone?

Not every franchisee of any business is successful.Call them, go tour a property with them, look at their websites, how many properties do they have available, do they answer the phone, does an agent meet you at the property, why kind of follow up do you get afterwards? 

I own commercial property in Mobile, Alabama.

I own commercial property in Mobile, Alabama.

I own commercial property in Mobile, Alabama.

I have had so many emails and phone calls.

Find out the values and rents of mobile homes for the areas you're looking to buy.

Once you have the avatar in mind, the kind of information that you want to be sending should be more clear- you could always send out surveys, get on the phone with them, etc, to find out what they prefer.