Here are some reasons I believe the values are poor 1) lot more home owners than home investors 2) if an owner wants an ADU they can easily add one that is exactly what they desire.  

This allows tourists/snow birds who are visiting to also rent a boat and keep it for however long they desire because they can dock it behind their vacation rental.If you have any questions let me know.

Their desire to lend on investment properties teds to vary from time to time so you need to keep in touch.

Which often times consists of people having the desire to purchase but not the means to.

This way you generally can refi or sell and 1031 at the time you want that is optimal versus a short term loan where you are forced to sell or refi on terms in the market you do not necessarily desire.  

I'd recommend going to some REIA meetings and see if you might be able to find some partners with properties in desirable locations that could be prime vacation rentals.

I own a 3/2 in a desirable, middle-class neighborhood in Houston.

(and the next property I buy will put me over 100%) I mitigate this risk by purchasing properties that are in very desirable rental areas and in good condition.

Then, you've got your monster house, in, by your description, not the most desirable neighborhood.

I work full time and am doing quite well in that regard.I do realize that there is a very large risk in thinking that I can keep it rented and perhaps I am being a little too optimistic in that regard but I do know that the area I live in is highly desireable for young professionals and I have a few friends who have been very successful in keeping their properties rented in this area.