I understand that that a home in Jerome Village would already have property tax, that would include additional fees for the roads, infrastructure, etc. and that it's based upon "millage" and the home's assessed value. 

Didn't mean to get political but I generally vote no on anything that will cause more rent control or increase my property taxes (all the special assessments).  

Also, there's the added risk of being compliant with federal regulations & state laws as well as properly assessing/vetting both the borrower and the property.

I have heard it’s cooled down quite a bit and assessing if it’s still a worthwhile option to consider as a market for str or even mtr? 

Underwriting will assess the performance and appraisal of the property based on traditional long-term rental comps.

For example, you buy a house for $1,000,000 but you say you bought it for $100,000How do they find out how much you paid for a house to assess their tax?

This could mean investing in property flips or purchasing out-of-state rentals for more stable income, but it would require letting go of the $1,350 rental income from the manufactured home.What factors should I consider for each option, and how would an experienced investor assess this situation mathematically?

If you look at the tax assessment, there will be an assessed value and the taxable value. 

Once you've pinpointed your objectives, it's important to assess your financial situation.

Get detailed quotes on these to ensure it’s cost-effective.Zoning & Permits: Verify that your current property allows additional homes and meets zoning requirements for multiple units.Rental Demand & ROI: Assess demand for singlewide rentals in your area to confirm it’ll be profitable after all expenses.If everything checks out, these could be solid additions to your portfolio.