I had to dispute it to gain an additional 6k on the appraisal.

Your mortgage, your equity and your gain do not matter.

I have nothing to gain by you investing in your market.  

All the above will give you, your management company, and/or your collection attorney some traction if it comes time to attempt to garnish wages or tax returns or levy their bank account.Some of the above may sound a bit draconian, but consider that you may have hundreds of thousands of dollars tied up in a property you're turning over for their unsupervised occupancy, and that they can do huge damage to the property in just a few hours.

But it's kind of like saying "does anyone want to back me in building a five star hotel" which you're probably not going to get any traction, unless you have a track record of working for a five star hotel developer for a few years and can demonstrate you truly know how to execute that type of development. 

We are going through a contentious divorce and I would like to buy her out, but apparently thats not very easy.If we sell the properties our gross earnings will be about 300k, while our net earnings will be around 150k, due to capital gains, depreciation taxes and realtor fees.My lawyer, who is not experienced in real estate investing, says I have to buy her out based on gross earnings, so I'd owe her 150k.

If I were to sell and build the two smaller houses, I could likely fund them enough from my gains on the current rental (and a little out of pocket) so they also cashflow ~$300-400/mo each.So, at the end of the day It’d be a wash or a little loss, cashflow wise, on one house and I’d gain ~$300-400/mo on the other house.

My question is, would I owe the full 20% capital gains tax on that amount?

Whatever you think you're losing on Airbnb through fees, you're likely gaining by having a consistent pool of potential renters.

Those are where I think I can make the most traction.