I have heard good things from the banks that you have mentioned, but it looks like you are limiting yourself by only having those few options. 

Or is your only option to tear down the current structure and build new?

Again I'm just exploring my options as this is my hard earned money that I'm spending and I'm not an iron fist person but like to be "fair" and "punctual" with any business.

That is the best option or simply ask your neighbour (and get it in writing) that you can put the fence in the same location.

We have discussed the option of selling to get the equity out of 'co-ownership' so that we can use the capital to pursue other opportunities. 

I'm not sure if @Jeff Chisum can do a condo or not, but he may be an option for you.

I at the moment saw this as everyone's best option. 

Hi all,I'm looking to house hack in the next year or two and have been connecting with brokers and looking on Redfin, Zillow, Movoto, etc.I'd really prefer to buy a Triplex or Quadplex, but I'm having a hard time finding many if any options.

You can apply this model to different types of real estate but multifamily, mobile home parks, and hotels are better options given the ability to buy larger assets over time.

I frustratingly see so many deal offers, particularly in Multi-Family space, where GP/sponsor is putting nothing or next to nothing into the equity portion and is collecting 2-3% acquisition fee/ 0.5-1% loan origination fee/ 1.5% yearly asset management fee/ 1-2% disposition fee and then 50/50 splits to 60/40 splits over fairly modest hurdle rates of like 14-15%, and it seems this latter structure incentivizes GP to take more risks particularly with debt options.