Make sure you write offers with proper contingencies that will allow you to limit your risk while you are able to lock up a good deal and still give you the time for your due diligence. 

I have a lead where a seller wants me to buy their property and then rent from me for a few years before I sell.How would I structure this deal if I want to lock up a rent back agreement and then wholesale the deal to another investor?

Do you have buyers for when you lock up a deal?

After the sheriff evicted the tenant and changed the locks, she hired a locksmith to drill through them so she could move back in.

Do you have the locks changed between tenants?

They were locking the doors and closing for lunch.

Also you don't have to worry what info the potential buyer obtains because you've already locked in the deal.

They have also arranged for the locks to be changed from the ones that Oak Park had access to - which were apparently the same master locks used on a number of properties from Mack that Oak Park managed.

However, the buyer wants me to just give him the lock box codes to the ones his interested in.

Get your RE license and then put your lock box access to good use.