Invest based on fundamentals in areas that will grow or be stable and with conservative underwriting and you'll be flying back to South Africa in first class to visit friends and family in no time. 

You never know, maybe higher, but I'd re-run with a more conservative rent just to be safe.

I'm pretty conservative and own most of my properties outright (no mortgage), so my ROI on most of my properties is 12-18%.

This is a very conservative estimate because rental demand is very high.

People with income like these would sooner buy a home than rent.In my case, if I believe a crash is coming I would conserve my cash, and invest in areas with better cash flow.

You may want to consider undercutting market rents by say 10% to be more conservative. 

My biggest stressor is having to share common areas such as the kitchen and living room with roommates I probably don’t know.I want to be aggressive when it comes to the multifamily properties but I also want to be a little conservative being that its my first purchase.

Having a larger tax estimate is good conservative approach.

This is especially true given the discretion to count it as GLA  is largely up to the appraiser who may choose to appraise conservatively. 

Conservative numbers rent 3/1 - 1100 month 1/1 - 800 month.