I'm Curious what it is that he should invest into specifically?

If there is a specific reason that music too loud during the middle of the day is a problem I would be clear with them.

Is there a specific property or strategy you’re going for?

Finding and funding your first deal is an exciting journey.When it comes to finding deals, a crucial step is identifying the right properties that meet your investment criteria, which can vary widely depending on your goals, the market you’re interested in, and your budget. 

Offer to pay the neighbors a reasonable amount say $50 - $100/mo. as they're doing you a GRAND favor helping you and besides that extra money may aide with commuting costs to work or a boost to their monthly budget or a their savings account!

You can cut up your 50k into a smart downpayment and renovation budget in the right area.

Perhaps you can find one willing to take on the project, someone who really understands your specific concerns.

Many Commercial lenders are not licensed, since there is not a specific license to originate 5+ Unit Commercial loans. 

I'd consider utilizing the tax experts option on turbo tax if you have any specific filing questions.

.- every investor reaches a point where their DTI is trashed and they have to move into different loan products. there are tons of lenders out there that specifically work with REIs & have many ways to navigate this. don't let DTI concerns keep you from moving forward. - LLCs provide minimal legal protection in case of an incident. work with an asset protection attorney to come up with a better plan if they are that concerned. also have great insurance and an umbrella policy.