Sit down with her, work out a plan (on a napkin is fine) and treat it as such.

Not just go off a verbal agreement or napkin contract that has you paying the mortgage for a seller who can leave you in the dust if he wishes ...

Just because it doesn’t meet the back of the napkin math, doesn’t mean it’s not a good deal for you.  

Quick back of the napkin math with very limited details tells me your extra payments on the points plus higher rate and PMI will match your initial extra 12% downpayment 25% vs 10%+3 points) in about 7 years.

Gurus will teach you to have the seller sign a napkin and put down $10 earnest money, but a contract is best.The investment in learning your states RE contract is worth it's weight in gold.

(iii) Changes in the amount of rental payments to cover additional costs in operating the rental premises incurred by the lessor because of increases in ad valorem property taxes, charges for the electricity, heating fuel, water, or sanitary sewer services consumed at the property, or increases in premiums paid for liability, fire, or worker compensation insurance.There ya go.

A person shall not occupy as owner-occupant or permit another person to occupy premises that are not in a sanitary and safe condition and that do not comply with the requirements of this chapter.

Just so you can see the disparity of value, the back of the napkin formula you would use to evaluate the park for the first strategy would be 18 times lot rent only (let's assume $600 per month) times 12 months, minus 40% for expenses = $77,760. 

Some of those variables are the size of the park, number of vacant spaces, number of POHs, number of vacant POHs, number of MH spaces, number of RV spaces, the park amenities, landscaping and trees in the park, the age of the park, underground infrastructure age and condition, park location, size of the market, demand in the market, water or well, sewer or septic, other utility sources and whether or not they are direct billed, deferred maintenance, cost of management, and more.However, if you are asking how to value a mobile home park, there is a quick "back of the napkin" way to evaluate a park that will usually tell you if the deal is worth a closer look.

There is a quick "back of the napkin" way to value a park that will usually tell you if the deal is worth a closer look.