Vesting is the exact name in which the asset is held. For an IRA-funded loan the payee on the note is usually written in a form like "ABC Trust Company, Custodian, FBO Sextant IRA #12345," and the custodian signs as custodian at the direction of the account holder. You direct, they execute. Your own name doesn't belong on the payee line, and a note made payable to you personally is a real defect rather than a cosmetic one, because the paper then says an individual owns an asset the IRA paid for.
Same vesting goes on the security instrument, whether that's a mortgage or a deed of trust depending on the state, and recording practice and fees differ by state, so your title or closing agent should confirm the local form. Have the custodian review the draft before closing. Most of them will, and most of them have a preferred exact string for the vesting line that they want copied character for character.
@thicket is right about payments, and here's the practical version. Set the note up so payments go directly to the custodian, with the account number in the memo, or use a third-party loan servicer that remits to the custodian. Servicing on a single note tends to run in the $15 to $30 a month range plus setup, and the servicer also handles the amortization schedule and year-end statements, which the custodian will not do for you. The custodian holds and records. Nobody in the chain is checking whether the borrower actually paid unless you or a servicer is watching.
