I would also not report this as a rental at all. Simply treat it as a reduction in the purchase price. This will lower your cost basis and might get taxed when you sell, depending on the circumstances. If you feel safer reporting the income as taxable, report it as other income on line 21 and don't deduct your expenses.
In addition to the issues outlined above, another factor is that you can't deduct a rental loss unless you renting with the intention of making a profit. In the rent back arrangements I know about (including one where I was the seller), the rent back payment equals the monthly mortgage payment. The utilities stay in the name of the seller until they move out. The rent is not based on a market analysis and is probably below fair market value. You aren't intending to make a profit, you are just holding in place until the sellers vacate.
With that in mind, you can only break even. Which means you can deduct the proceeds you receive (mortgage payment) agains your expenses (mortgage payment). You can't deduct other expenses like property taxes and mortgage interest--and why bother since you can fully deduct them as normal household expenses on schedule A. You can't deduct repairs that would show a loss if you aren't renting for profit. And any repairs you made during the 59 dat rental period were not really "so you could rent it to other tenants." They were in preparation of you moving into the home. It will look to the IRS (correctly) like you are trying to get an impermissible tax deduction on repairs made to your personal home.
So my suggestion is to skip all the paperwork entirely and just treat it as a price reduction on the sales transaction.
