This is eerily similar to the unsecured loans I've made and haven't seen a payment on in over two years.

Don't change jobs or income yet.Once you do and you think you can manage the payments based on your new income, maybe once you get the rooms rented.Then if you want to switch there are plenty of opportunities. 

Payment TermsContract Value: $[Insert Amount].Deposit: $[Insert Amount] due before the commencement of work.Payment Schedule: Payments to be made as follows:[Milestone 1 and payment amount].

There's no reason to provide details, though I do let people know if anyone asks that we do not accept bulk up-front rent payments or anything like that because I absolutely do not want a prospective tenant to think that someone else swooped in with a bunch of cash last minute.

If the other two parties want to flip a house maybe they can do just that as partners and then sell you the house which you can buy with a primary home loan with low down payment.

In this case, since they are borrowing their payments, these would get added to the principal balance each month, and interest would be calculated on that.If, for example, the interest rate on the note were 10%, they would implicitly be borrowing their payments at that rate.

Do they require payment on site or do they give you a certain number of days to close the transaction?

Your son is responsible for making payments on time or ruining this seller's credit. 

Because the payment is coming from the tenant, and not the surety bond provider, claims are always processed without a fight.If you are interested in considering a surety bond program, I recommend Obligo.

Instead of moving into another single-family home, consider house hacking a duplex or triplex, this allows you to use low down payment loans (FHA, conventional) and offset your mortgage with rental income, accelerating your path to financial freedom.