Master lease question

found a park i am interested in… was advertised as no POH’s, come to find out there are 14 leased poh’s…he is willing to guarentee space rents thru a master lease until ALL homes are sold off. being new to this business…what kind of issues will i run into with this type of purchase agreement. is it best to have an attorney prepare master lease? how would you handle the guarenteed rent’s? would you escrow the rents for a period of time or just collect collect monthly like rest of the parks tenants? also seller is not willing to carry back any financing and i know lenders don’t like poh’s to be over a certain percentage. any thoughts would be much appriciated!