There is no additional valuation for the STR business.In the end, past performance is not an indicator of future success.

(replacing the original HELOC debt) However whether the interest for the  additional $200kish of loan  will be deductible will depend on 2 things: -How were the renovations paid for?

Given that you're not married, that adds some additional complexity.  

Additionally, understanding the rights and responsibilities of both tenants and landlords under this program can foster better communication and smoother interactions.

However, in most markets I would assume an additional full bathroom would not only command higher rent, but would increase the equity and appreciation.

It sounds like you’ve got a solid foundation with your rental property, and I love the ambition behind your plans to build a property management and maintenance company—it’s a great way to take control of your investments while creating additional opportunities.Best of luck to you! 

There will also be closing costs to refinancing into DSCR.Lenders need 6 months to refinance a loan, anything sooner, you're probably paying a good amount of points / DSCR has to be rock solid.There also may be additional costs in maintaining your property.

Additionally, the rental arbitrage strategy is not investing, its operating a business.... an extremely risky business.

Quote from @Eric Huntermark: Additionally, as I'm thinking about conventional loan products as well.

In addition, if you're actively flipping properties in the area, I currently have time on my hands and I'd be happy to support you in one of your projects in exchange for learning in depth about the process.