You don't need to use a DSCR loan unless you're buying properties that don't conform to standard guidelines or are trying to do cash-out refinances prior to the 12-months seasoning.It will be safer, and you'll sleep better, if you can: get the additional $10k from working, get a 5% discount on a house, find a property where you can add value through renovations or re-purpose and end up <75% LTV (aka., buy at a discount).

In Seattle the requirements for a separate panel in each unit, usually separate electric meters, separate heat sources, separate hot water heaters and plumbing runs, etc make legalizing a non-conforming unit pretty expensive.