Screen as best you can and hope for the best.The worst on paper can turn out to be the best tenant you ever had and the best on paper could be your worst.If you screen, check references, verify employment etc you increase your odds of a better tenant but things happen.Look for reasonable credit (your call)No evictions in last 7 yearsNo Criminal (be careful not to discriminate against new laws)Make 3X the rentjob stability 2 years plusIf any items are not perfect then get a bigger deposit to give you a buffer if they get behind or stop paying.Start an eviction (after proper notices) as soon as possible after a tenant misses a payment.

How much buffer have you put into your projections? 

I know that some people like the idea of some sort of "anchor" or "stability" with a long-term tenant, but if you're making 2-3x the revenue with an Airbnb/short-term rental that of a long-term rental, you've got a buffer built in should you need to transition from STRs to another model.The bigger question for you, though, is what the regulations are in your community.

Protect yourself by building in enough buffer and enough of an emergency fund to cover the downside of a deal.

Keep that equity as a buffer incase the market drops and let pay down do its job.

I can at this point I do not have to work for the next 6-8 months and I will be able to maintain my current lifestyle which I believe to be a good buffer into getting into a 1099 position.

Hence you need a large buffer.

Keep the 50k remaining as a capital buffer!

Would you simply subtract the tax delinquent amount from the purchase price, or would you build in more of a "buffer zone" to account for other expenses and/or tax increases in the coming years?

Now, I may be a whole lot more timid than you, but personally I'd be cautious about diving in without any built-up buffer to cover what you already have.