Isn't there risks on both sides of the table when using this closing procedure?

Bring a viable deal to the table and you will have investors interested.

We have 5 properties in the mountains, upstate NY that we rent by the night and week, year round. 

I would agree with @Daniel Huang Partnership % split is based on what each partner brings to the table such as experience, who found the deal, cash, credit, time involved etc.  

However, I don't know how well, if even possible, you could negotiate with a bank on a short sale/foreclosure.But if, while I'm looking at different properties, I can make note of how long it's been on the market and bring it up in the discussions, I want to be a least minimally educated about the average time on the market so I don't get laughed off the negotiating table.

Ask yourself what are you unique skills that you bring to the table?

This hits home for me, because the literal mountain of info there is to ingest and avenue to get there.

I can bring my own money to the table but if I can use OPM I am happier :)Other then your own pocket - where are investors raising capital for rehab?

Any ideas on the best way to bring him to the table with the best possible financing?

You definitely want the exposure that the MLS will bring, along with the network and exposure that a good agent will bring to the table.