This will significantly harm DTI.Unless you're ready to give up the FNMA-subsidized 30YF residential loans already, or unless this is the last mortgage that person wants, such arrangements rarely make sense. 

One of the many tax traps to avoid in this complex area is including terms that resemble a lease or a sales agreement rather than an option.

The 2nd deal was sold in October of 2019 and his net profit per our arrangement was $15K.

The worst case scenario I can come up with is the bank finds out about the arrangement and exercises the acceleration clause on the note.

It really does, because syndications are structured differently.One of the common arrangements is when a syndicator wears two hats.

A 30 day close shouldn't be unreasonable, you'll still need to do due diligence on properties and arrange closing with title.  

You arrange for that if you want it.Taxes will depend on when you buy the property and if taxes have already been paid for the year. 

I can arrange around 60-80k as down payment.

It’s definitely anywhere USA. 12 years living there and I never saw a home that resembled an Alaskan lodge or has a true view of the mountains.

@Calvin KwonThere's a difference between a cost sharing arrangement and subleasing, and different tax treatments follow.It's unclear from your OP what (1) arrangement you have with the other individual, if any, and (2) the economic reality of the transaction (e.g. what it is in substance).