How do we have a fair split of a partnership

[Tony Wu]

My partner and I are interested in entering into a partnership finding below market real estate, improve, and then rent out or flip for a profit.  Assuming that we each split the up front cash needed 50/50, my partner has recently retired from his full time job and able to act as a general contractor role dealing with all aspects of on the ground work, however, I am the one who is still employed with a decent income from W-2  (my partner also has maxed out his credit due to his other real estate endeavors) and therefore, the plan is for me to obtain finance if the deal is financeable or, if not financeable, we will each contribute equal amount of cash, and then cash out refi using only my credit.  

My question is - how to fairly partner up considering our situation? I would think 50/50 make sense but on the flip side I am a bit concerned that only myself is on the hook for the loan, assuming LTV of 70%, I am thinking I would have 85% of skin in the game as my partner would only risk his 15%. Anyone can chime in to shed some light to help me come up with a fair split?