I think the rent would make a good dent in your mortgage payment but you would still be paying some money out of pocket after all expenses.

I've included an example below to help illustrate this.So different lenders have different rates (which do vary even for DSCR loans) but these are factors they all consider.See example below:DSCR < 1Principal + Interest = $1,700Taxes = $350, Insurance = $100, Association Dues = $50Total PITIA = $2200Rent = $2000DSCR = Rent/PITIA = 2000/2200 = 0.91Since the DSCR is 0.91, we know the expenses are greater than the income of the property.DSCR >1Principal + Interest = $1,500Taxes = $250, Insurance = $100, Association Dues = $25Total PITIA = $1875 Rent = $2300DSCR = Rent/PITIA = 2300/1875 = 1.23DSCR lenders generally let you vest either individually or as an LLC.

Evaluate operating expenses, including property taxes, insurance, utilities, maintenance, property management fees, vacancies, and capital expenditures (CapEx), to ensure accurate estimates.

I calculated the numbers assuming 1, 2, 3 and 4% annual rent increase.At 1% increase in rent, it takes me ~15 years to be cashflow positive annuallyAt 2%, it takes ~8 yearsAt 3% 5-6 yearsThis assumes 0% vacancy.If I look at cumulative cash flow i.e. net gains (loss) from (income - expenses) projected over all years of ownership, those numbers are worse.

You will have those expenses sooner or later.

(source)It also states this:  The following requirements must be met by taxpayers or RPEs to qualify for this safe harbor:*Separate books and records are maintained to reflect income and expenses for each rental real estate enterprise.

The cost of money would be considered an expense.

However, you can deduct any expenses you have while at your destination that are directly related to your business."

All of my LLCs have their own bank accounts, books, expenses, etc.But what else do i need to separate? 

Reality is that repurposing a tin can into living space is expensive.