$50K is a pretty low benchmark for buy-and-hold's up here.  

The European Commission, in its investigation of the Libor scandal this year has uncovered two international banking cartels that were used to influence the Libor benchmark interest rate and set bid-ask spreads.Royal Bank of Scotland (RBS) was given immunity by the Commission for revealing the existence of the first banking cartel.

I think this is a pretty good benchmark for what most investors in much of the country (though certainly not the whole country) could expect for a similar job.

When my rental portfolio reached a $4k monthly net (right in line with your $40,000 income benchmark), I began wondering why I was striving so much for early retirement and "freedom." 

The other is a hybrid model, where you intentionally look to hold properties for a predetermined period of time (say 5 - 7 years) with the plan to sell the property.Second, the benchmark for me is a minimum cash flow, neighborhood & school district quality and overall location. 

Use that number as a benchmark for evaluating this and other deals.  

Do you know other landlords in the similar market to benchmark with?  

I did some calculations, CoC as an alternative to CP which seems very subjective no(beyond an initial benchmark)?

CAP rates vary by market but as an example, if you are comfortable with your purchase price on the larger facility, you might just use that CAP rate as a bench mark for this smaller one.  

I have also used proof of funds letters from a private lender, basically a letter on his letterhead stating BenchMark has available "$200,000?"