Most Class C/D areas will pencil to positive leverage, if you use generic underwriting assumptions.  

@Mike TikhRecommend you first figure out the property Class you want to invest in, THEN figure out the corresponding location to invest in.Property Class will typically dictate the Class of tenant you get, which greatly IMPACTS rental income stability and property maintenance/damage by tenants.If you apply Class A assumptions to a Class B or C purchase, your expectations won’t be met and it may be a financial disaster.If you buy/renovate a Class A property in Class D area, what quality of tenant will you get?

@Loan NguyenRecommend you first figure out the property Class you want to invest in, THEN figure out the corresponding location to invest in.Property Class will typically dictate the Class of tenant you get, which greatly IMPACTS rental income stability and property maintenance/damage by tenants.If you apply Class A assumptions to a Class B or C purchase, your expectations won’t be met and it may be a financial disaster.If you buy/renovate a Class A property in Class D area, what quality of tenant will you get?

(This, of course, depends on one's assumptions about future appreciation; the prospects of which I have my doubts.)

It sounds like inventory is pretty fixed in the Maui short term rental market, but I'm not sure if that's a safe working assumption for the long term.

All of my assumptions were based on that 2 unit residential and are fairly accurate between rental rate and ARV. 

Absolutely love your #1 My assumption is the OP will stay pay for an overly complex structure that adds limited value except to the pockets of the service provider

Once you see how much it cash flows, you can divide by your total cash investment to find the cash on cash return, then make assumptions about appreciation and mortgage paydown to find your total return.  

In conclusion, I think a general assumption of ~15 years ROI is reasonable, and I believe if you really dial in the usage and match the system config to optimize, you could drive down to a 8 year ROI.

The only assumption I make is that the house will need to be gutted.