I'm sure the place will be a noisy construction site for at least a year.I want to avoid pointing fingers, but we put our trust in an HOA to take care of things, to separate and insulate ourselves from the emotional responsibility of maintaining and protecting the value of our property. 

Old single wides will bleed you if you have to constantly maintain them

They have worked with these people, know their skill level and reliability, and they have an interest in maintaining a long term relationship with them as well as you.

Conversely, your friend might work harder and be quicker to raise red flags in order to protect you and maintain the relationship. 

My income is high six-figures/low seven figures, i am an active investor in hedge funds so I rarely keep much cash available, my credit score is 800+ and I'm smart enough to know that I can get hurt badly venturing head first into an area that I'm not so well versed in.I am not in need of current cash flow (although I don't mind it), and, I am looking for well maintained Class B/C/D buildings with a true and "real" 5%+ cap.

The landlords that I know that get tons of maintenance calls are the ones that don't property maintain their units.

It had 2 kitchens a huge living room, a pool table room, 5 bedroom & 4 baths.They are interesting pieces of history that require some very unique knowledge to maintain, but people love them.

The biggest drawbacks to multi-family is that often you have to pay the water (single water meter for the building and thus no way to bill back to tenants as you can with single family houses), you typically have to maintain the yard, and your average tenancy duration is likely to be slightly lower (people who prefer to live in single family houses move slightly less than people who live in apartments/units in multi-family properties, especially once you are in areas better than 'C' quality).

While these are very good and strategic thoughts on your end, it is imperative that you maintain within the guidelines of the city's regulations and adhere to their codes for the safely of the public and for you as the owner or landlord. 

I build and maintain Koi ponds, Waterfalls, and offer Lake management services as well.