NEVER rent to YOUR family. Someone will take it wrong and tell the rest of the clan what a jerk you are. What happens to your taxes if you liquidate the stock? Can you use the stock as collateral?
At this time LLC and Corporation decisions are unnecessary if this is your only property.
Self directed IRAs must be an arms length transaction with all of the funds coming from the Self Directed IRA. You must first legally fund an IRA and accumulated the cash there. You can then convert it into a self directed ROTH IRA. There are annual fees with the custodians of self directed IRAs. Do not convert your Roth until AFTER you have the working capital in place. Early conversion means wasted annual fees.
Research Illinois Land Trusts as a way to hold title, achieve privacy and avoid probate. Buy lots of insurance ($1,000,000 general liability). Then buy more insurance (From 1 to 5 million commercial umbrella). The umbrella protects you from Extra stuff not covered under a general liability policy.
Your company should lease the unit from the trust with the right to sublease. Get a lawyer for this.
Once you have acquired a few then worry about your business entity.
Read the book "Lawyers Are liars" by Mark J. Kohler before taking another step.