@Nicholas Nikel yes it’s small claims and yes it doesn’t cost a lot to file, but it costs a lot of time and collecting on a judgement, assuming you win, is even more work.

However, it can cost a minimum of $100,000 to do it right.It's been a struggle with lenders and I'm seeing less and less flippers/investors build out ADUs for resale because of it. 

It will cost a lot of money to split the house.  

For example: 1500 sqft house, looks in ok shape, probably cosmetic mostly, in my area of Seattle (things cost a lot here), I would put on $25/sqft, so rehab estimate is $37500. 

I have a soft spot for the island as I had a lot of good times there, it has the best bars/clubs by far (don't know if they're still there, but we had Ocean Drive, Springfield Inn, La Costa, Shenanigans, Steak Out - I played some of these places!)

@Jared HebbQuiet title is a legal action (lawsuit) to clean up title.Depending on the state it can cost a few grand to $5k+.If you are the buyer you should not pay a dime - the seller should be paying this and/or his own title insurance should (assuming they had title insurance).They also take time, this will not be resolved in a month or two.

@Jeff Costa do you find most deals are in the commercial space are pocket listed and pushed to other buyers who they know have the funds and experience to close deals?

Your cost to acquire project entitlements would be limited to; third party cost, any option fees paid to the landowner plus the value you place on your time (which includes your learning experience).Investing your time and a defined cost as noted above mitigates your concerns about risk because it's knowable and tolerable.

As mentioned above, remember carrying cost as well as selling cost.

This is the quickest way, but will cost a little more in rate and fees.Paying a broker a fee is not terrible.