You used your leverage and ability to spot a deal very well and continued to grow while mitigating your risk along the way without losing any additional rental income. 

Thus, proper year of inclusion is the 2018 tax year.Constructive receipt is a facet of the cash basis method of accounting designed to mitigate "pay me later" deferral schemes. 

My mentor and I had a lengthy conversation with him concerning the risk involved, but the rewards are surpass the risk so as long as we mitigate it.

Any thoughts on how I can mitigate the risks of doing deals with other people.

@Tom DonnellyManagement is a factor, which can be easily mitigated by paying someone or if you can do it, but it is something to consider.

That is one strategy to mitigate the loss of the summer rental income, a lease from Aug to Aug, but knowing the tenant is going to break the lease in May, but will pay basically pay through June.Another cost to be aware of is that college students tend to be rough on stuff, so be sure you are accounting for appropriate repairs.This isn't to say don't move forward, just make sure your analysis is sound. 

I think this risk could possibly be mitigated by imposing a 2 or 3 day minimum to avoid the 1-day party demographic or maybe avoid marketing on AirBnB and focus on sites such as VRBO (still studying this myself). 

S-corp is actually used to mitigate the self-employment tax, however it's case-by-case and may not always work1.

Yes you are avoiding the problem initially but there are several ways to mitigate and eliminate the tax forever given time and planning.  

It's my job as an investor is to anticipate and mitigate risk, right?