And are potential guests interested in staying at a STR in a basement that can have occasional squeaky floors from time to time?

Occasionally, I will get an objection from an off-market homeowner that "might" sell saying...

A few things to keep in mind:Section 8 requires the property to pass an inspection based on HUD’s Housing Quality Standards (basically making sure it’s safe and well-maintained).The rent you charge has to align with Fair Market Rents (FMRs) in your area, so it’s good to check what similar properties are renting for.You’ll still be responsible for maintaining the property, but the upside is that a chunk of the rent is guaranteed by the government, which can provide steady income.Check with the local housing authority about any specifics for your area—every jurisdiction does things a little differently.This could be a great niche if you can find a good deal on the land and make sure your expenses (like maintenance, insurance, and occasional vacancies) are covered by the rental income.

Learn how to consistently hit singles and doubles, and don't be ashamed to take the occasional walk. 5 years is a very short time frame to go from no RE to financially free (although you may already have property, which is an awesome start). 

When you are consistently above 820, you may occasionally hit 850.    

This is an IRA, just like any other self-directed IRA; however, it allows you to connect your IRA to the following: 1) You can use a checkbook IRA LLC type structure, for example, if you are purchasing individual rental homes, or an occasional fix-and-flip.

So I'm very confused asking if there are any institutions that will take bitcoin as down payment (Which seems extravagantly easy because a bank or lender  could/would simply convert to USD) vs you stating that they take them as collateral, which seems like the more difficult task.

Ideally, I’d have an Airbnb down there (for occasional personal use) but have received some feedback that an out-of-state Airbnb would be too difficult to manage.

So you're making your standard monthly mortgage payment, while simultaneously making occasional lump sum prepayments via the HELOC.

For residential mortgage, an LLC needs two years of its own tax returns or occasionally, a local credit union where you have an account will ok it.The bigger question is about your partnership.