有很少银行给 IRA 贷款, 而且要求很严

They are small banks, not normal large banks. You have to search hard to find them. You need to borrow at least 50K, and have 20% reserve. The rate is certainly higher than primary residence.
Good thing is they won't require income or employment verification.
From IRS requirement, the loan has to be non-recourse, ie. the loan is only secured by the property. The meaning is two fold: 1) not secured by the IRA account, 2) nor personally guaranteed. Also, the part of the profit that you earn from the loan will pay tax, called Unrelated Business Income Tax (UBIT).

Hope this helps.
sunskitehomes.com