I am with @Jeff Filali on this one... his math formula indeed makes sense  (heck if you want to see real life documentary how I am executing his formula in real life simply visit my blog).. 

Your lender will need to see the executed lease as well as proof of the historical expenses, as well as, a well considered extrapolation of expected future expenses.I'm a commercial lender in Andover / Blaine; happy to help.Take care,Mike

If you get a lawyer to do it you need to make sure that not only the state disclosures are prepared and fully executed, but also the local ones.

Again I'm also not a lawyer or offering legal advice, but this might be tough to execute because when you refinance a lender is going to want you to have 20-25% equity which you would not have unless you kept some of these loans active and even then most lenders will ask about private loans.

Here's a sample of fine print:“Borrower shall occupy, establish, and use the Property as Borrower’s principal residence within 60 days after the execution of this Security Instrument and shall continue to occupy the Property as Borrower’s principal residence for at least one year after the date of occupancy, unless Lender otherwise agrees in writing, which consent shall not be unreasonably withheld, or unless extenuating circumstances exist which are beyond Borrower’s control.”Different lenders have different "fine print" statements that may be more grey and confusing.

@Kole Kingslien  Guidelines for land contract:- Payoff of Installment Land Contract Requirements When the proceeds of a mortgage loan are used to pay off the outstanding balance on aninstallment land contract (also known as contract or bond for deed) that was executed within the12 months preceding the date of the loan application, Fannie Mae will consider the mortgageloan to be a purchase money mortgage loan.The LTV ratio for the mortgage loan must be determined by dividing the new loan amount by thelesser of the total acquisition cost (defined as the purchase price indicated in the land contract,plus any costs the purchaser incurs for rehabilitation, renovation, or energy conservationimprovements) or the appraised value of the property at the time the new mortgage loan isclosed.

If you have pending executed contract, they cannot simply sell to someone else at this time.

My question still remains as what gaurantees that owner will let you can execute the option 30-100yrs later.

My question is, if you have the contracting company, and the hard money lender, then why not execute the rehab?

The best way to acquire this MHP is probably via purchasing the non-performing note and either executing the foreclosure or pursuing a quitclaim deed.