MHPs are income stream investments and valued as such. 

A couple of "unrealized" income to consider:1.

I would focus on screening your tenants for background, credit, and income to try to avoid an eviction and excessive damage to your property to minimize your turnover expenses and vacancy loss.  

Are there lenders who will consider my past str track record when determining Debt-To-Income ratio in regards to turning my current house into an income producing property?

Increase income, reduce expenses, save, and invest.

While navigating these alternatives, you can gain STR market experience, build equity, and potentially generate income to improve your credit score over time.

It's definitely not a terrible idea to own real estate outside of a retirement account so you can take advantage of all the tax benefits, especially using the depreciation to reduce your taxable income from a w-2 job.

Great question Luke, As a lender we use your personal income and the income from your properties to qualify you for the mortgage. 

Hi,I have 3 homes and need to find a template/form where I can put in all the original purchase information - or the most current refinancing information and all the current rental income and expenses.

A DSCR loan (Debt Service Coverage Ratio) type loan would look at the rental income and expenses and determine the amount it could lend based on that.