Hopefully I can upgrade myself from investing in real estate to Note in a year or so.....  

If you have a 6 bedroom in an area that does not have a university (students looking for shared space) or is in a family friendly place it may sit vacant longer between tenants.For Capex, try not to use a generic number - look at the roof, furnace, hot water tank, kitchen - when will each need to be done and what will it cost?

However, if you know and have a relationship with the person/team that will be doing the rehab for you in your absence and trust they have your vision in mind then you are in a better place to start. 

Similarly, if you put all Class D tenants in a Class A 4-plex, what do you think will happen?

If you are living in a place that is satisfactory why not change the arrangement with the landlord?  

So a 500k house in a good STR area should be getting 60k to 70k in revenue.

Quote from @Elizabeth Rose: @Josh Bowser this tip of doing a quick search on county GIS or software to see if homes in a neighborhood are owned in personal names or LLCs is gold, thank you!

I have a full time job in  a totally different field and I manage 2 properties.

@Bryan Cavellier, You can 1031 with any US property including Guam, the USVI and ...drum roll- The Northern Marianas Islands (go figure but I actually had a realtor from there in a class of mine recently) into any other US or one of those territories.  1031 is a federal statute so it's applied the same in all locals with just a few variations state to state at the state level. 

Sell one of these in a few years and use your accumulated wealth (appreciation)  to buy a STR at that time.