I would suggest that you interview several Realtors and ask them the following questions, to ascertain if they are truly Investor Friendly, or if they are throwing you a sales pitch.1.

@Sam Grooms it's not as simple as certain clauses to include, I would hire an attorney.

Are you able to ascertain enough from the underside aka within the structure?  

I found what seems to be a great deal, but want to be as certain as possible before committingThanks for your help!

It goes on to say that the true current value of a property can only be ascertained by a licensed appraiser (which I am not).

Keep in mind if it is a recorded mortgage some type of probate will be needed to ascertain who inherited the mortgage. 

Now, keep in mind that the deal is, you sold me a contract to buy, that means with good title unless otherwise disclosed.I'll sure be looking at you if I bought your contract and in 3 or 6 months (whenever) I can't buy for any reason other than default of the seller and even in that case, the deal may be investigated to ascertain if that contract was good.

Although, that's hard to fully ascertain as I recently just moved from Colorado back to my roots here in Minneapolis in order to live a little cheaper and save some money.

If you get the address there is enough info out there to ascertain a value.That said, if you don't know what you would pay you might as well stop sending them letters. 

The value is also considered compared to similar assets in similar condition, the reason for comps.The reason MH dealers are in a position to rip off unsophisticated buyers is due to several issues. 1. an appraisal is never used in seller financing these old rehabs, or throwing lipstick on and 2, The value is not easily ascertained by the public.