Even those who lost their homes through foreclosure or short sales still needed a place to live and desired to stay in the same general areas so they became renters.It is important to consider how the industry/business sectors which employ your target tenant pool are likely to perform during a downturn.

You can also ask the seller of your target replacement property to accept the note as part of the consideration/payment for your replacement property, but most sellers will not touch a third-party note. 

My target is at least one or two per year.

The passive investor has to weed out sponsors with that attitude (which is easier said than done).  

Build your foundation before you build your house and you'll have a much easier life and deals will get done easier and quicker than always being one step behind your deal.

@Amanda Gust - Pros for the SFH:- It might be easier to find one renter than 2 separate ones.- The 900 might be a better quality tenant than the lower price- As @Nicole Frawley said, it would likely be easier to BRRRR than the other (and easier probably to sell down the line if you wanted to)Cons:- If the SFH takes longer to find a tenant for, you have no income, unlike the 2 unit, you might have staggering vacancies and still have something coming in.

Will raising rents to $500 be easier said than done? 

They are way easier to work with in my opinion and as you grow, they will be more willing to be creative with your future deals if you keep a good track record. 

If you're trading 8% cash-on-cash for 10% cash-on-cash I guarantee you'll blow that 2% marginal gain in travel costs.That said, those costs do get easier with scale. 

Cheaper and easier than dealing with a post break in drama or vacancy.