Doing it this way reduces the possibility of both units vacating at the same time.

Had we been able to vacate and renovate this unit, average rents would have climbed to $2,933.)Following completion of the remodel and stabilization we marketed the property for sale and found a buyer within three weeks of marketing.

The major issue is that she's asking if I could vacate within 3 weeks and pay prorated rent for the month of August, but she'll offer $500 to assist with moving expenses. $500 doesn't really cover a lot, and I am also tasked with finding a suitable home in a few weeks.

The tenant is being evicted and supposed to be out this month (I have three contingencies: Seeing the other unit, tenant is vacated and inspection).I believe once the other side is renovated I can bring in ~$600/side, so ~$1200.I received a cost estimation with my pre approval letter of 85k which has my PITI as ~$650 so I'll use that.

Since you have to return security deposits within 21 days of the tenant vacating, you can certainly get stuck with storage or disposal fees that you can't deduct from the deposit and aren't worth going to court over. 

Our industry is build on second/vacation homes.  

All on vacation of some kind or another.

The lease was written for an year and ends in July 31st but I doubt whether she is going to voluntarily vacate.

Short term vacation rental.

This would change your tax situation and I can't give you tax or legal advice, just throwing out ideas.With the self-directed IRA, you can't use it to buy certain properties like your own residence or a vacation home.