You might also want to consult local property managers or rental market reports for a more accurate picture.When it comes to estimating CapEx during preliminary analysis, without visiting the property, you can use a general rule based on the property’s age and condition.

If the residence is inside a gated subdivision or a controlled-access buildingthat is governed by an owner’s association, a letter from the association acknowledging the use and grantingaccess to occupants of the rental unit will be required as part of the application.A short-term residential rental requires a Conditional Use Verification (CUV).A short-term rental use is unavailable and prohibited within a residential unit or a room within a residentialunit that is located in an apartment building.

@Darrell Overly  there are certainly enough mobile homes in the area around phoenix (East Mesa/Apache juction) but your issue may be the age of the homes and any limitations the park has on renting.   

I also wish I had started thinking about REI at your age.

I'm currently helping my aging parents, and I need to be spending more time taking care of them.

So your number of 715k may not be too far off depending on the square footage and also the age of the cabin.For anybody to suggest otherwise without knowing more information on your specific cabin isn't giving you the best advice to be honest. 

We had a third party report done for our prior offerings (similar to how a mutual fund has a third party verification report to verify the returns). 

In Illinois, the minimum age to officially become an unlicensed assistant is 18.

We plan to rebuild, but our neighbors are aging and do not wish to go through a rebuild.  

I built my first modern 7 years ago and like you agree that some (not all) moderns will age out.