Don't ask on this thread, as most tax strategies require a good understanding of your current and future tax situation first.

Install additional stackable W/D units in the garage (requires some electrical work).2.

You are required to disclose that debt, and it will be a fairly easy catch for an underwriter, even if it's not on your credit report. 

What documents do they require, what credit scores do they allow, how do they verify previous rental history, etc.?

The BRRRR strategy is doable for a newer investor, but it requires a lot of effort, consistency, and hands-on involvement—it's not exactly a passive way to invest.Whichever route you choose, if you're taking on the bulk of the work to analyze deals and select the best ones, it’s important to ensure your partnership reflects the time and energy you’re putting in.

Another option is setting up a legitimate virtual office through companies that specialize in meeting Google’s requirements—just make sure they provide suite numbers and not P.O. boxes. 

These loans focus on the property’s income potential rather than your personal income, so they don’t require W2s or pay stubs.

They require a lot of work and attention.  

The actual penalty varies but it's often a step down or if a 5 year prepayment penalty term, it will be 5% of the original or unpaid mortgage balance if refinanced or sold in the first year, then 4% in the second year and then on down (the exact penalty varies which is why I mention both the original and unpaid mortgage balance.

That's the only solution and it doesn't require fifteen paragraphs to explain or justify.