Since we have already lost about $9k in rent and with unknown timing, this seems to be a worthwhile alternative to stop our losses. 

One alternative would be to set up an interest bearing bank account and simply put the accelerated payments into that instead of paying down the mortgage.

I have a column open for notes and prices for material costs.

If conventional means would not be the way to go (I don't know if you have SSI or anything else + the rental income), but if that doesn't allow you to qualify, there are alternative loan programs that don't look at personal income at all. 

For the sake of this example, we'll assume the money partner is all cash and let's use $200k as the purchase, $40k rehab (includes my salary for me doing the work and materials), 8 week time frame ($12k in salary to me out of that $40k), resale of $300k.

@Calvin Lin Vegas builders were stuck in a mediterranean style of home for a couple of decades before finally expanding into alternatives like the style you show in the photo.  

He won't give a bid on the entire project... he just gives me a "not to exceed" bid for labor only (although he always exceeds it by quite a bit) and leaves the material estimating and purchasing up to me.

I'm currently learning about material costs and how to install everything I'll need to.

Good example, I had a slight pricing and supply chain issue on some needed materials, I could have thrown $ at the problem but instead I made some calls and I bought a partial rail car of the material, lined up my own motor carrier, was able to cut 2 middle-men out of logistical chain, 1 1/2hr drive to rail yard to personally supervise and we got out materials, faster than anyone could deliver, for 30% discounting AFTER all associated costs.

You will need alternative sources.