Would this be a letter of intent or promissory note?

Do you recommend doing a lease termination letter, just to have something in writing?

We found our forever home in the neighborhood we wanted by driving the entire neighborhood, adding the properties using DealMachine, and then sent them all handwritten greeting card letters stating that we're a new family looking to move into the neighborhood and if they had any interest in selling to please call us. 

Like that report ot the 3 credit agencies and send letters for you?

With the sellers, we agreed upon a down payment, a purchase price, a monthly payment with no interest, and a 10 year term loan with a balloon payment due at the end.

Have the term be for a 10 year balloon or so, and refinance it then.

They will typically request an architect's letter that confirms that the project is as of right and requires no variance, which tends to be the case.

The 'sales price' is $600,000 (any outrageous number), but the balance on the sales price (600k - 12*2000) is due as a balloon payment on month 13.

.- Most of the deals that came our way were for 60-70yr old wood frame buildings, that had been owned by their current owner for 25+ yrs, and we felt there was a definite risk that the economic viability of the asset was less than our planned (buy and hold) time horizon, and we were also highly skeptical of the insurability of some of these buildings or that the cost of insurance would not balloon once the ownership transition forced the insurers to reassess the building.Ultimately we pivoted to retail/light commercial mixed use properties.

I think if you can write a solid letter of explanation stating that you are going to commute to Colorado from Washington for 4-5 months out of the year for your job (and why), that should be sufficient enough to run this as a primary residence.