If the holding time does not effect your profit margin too much I would wait to maximize the buyers for the property.

Those are sunk costs and will eat into your profits.But on the other hand finding reasonable contractors to rehab a mobile home for a fair price takes work and time, but in the end the home is more affordable and you have more potential buyers for the same or better profit margin.They both work, but the latter will yield better returns.  

by arranging for a capital partner so you can maximize those few deals you get with all the competition etc.

He has other priorities and wants something easy, and turnkey investments yielding about 7-9% returns per year seem to fit the bill.

(hate the ceiling pull down.) maximize all arenas. laundry and other such zones with slatted shelving that extends up. the slats keep it light while allowing extra space for things used not so often. slatted shelves behind doors in bedrooms etc. when appropriate. instant hot water tanks save space. keep living spaces open for an airy feel. 

(https://www.biggerpockets.com/renewsblog/2015/12/20/plan-holiday-travel-maximize-tax-deductions/)

I would like to have the other units totally renovated within the next year to maximize its full potential.

However, rental yield will be low.

So, now that we know this deal could potentially yield me $660 a month when we move out and refinance, this would be a great investment?

I have three options:I can sell to my tenant - most of my tenants are interested in home ownership, eventually.I can sell to an investor - I only rent M2M so I can offer a home that produces income or can be vacant in 30 days notice.I can sell to the open market - most of what I own is SFH, so I have a broad market to advertise my house...I can also sell my home below market (because my purchase price is right) to get out quickly if I need to and still make a considerable profit.Multiple properties may incur higher PROBABILITY of a bad thing happening, but it will yield you a higher PERCENTAGE of return on your investment IF you stick to your investment rules.My largest "contrary to the popular belief" is that I buy not to generate large amounts of cash flow (although each property does @Justin Fox brings up a good point that it isn't just what you have left after you pay PITI), but to keep my equity safe and building as I own and maintain the property.