If the numbers make more sense on the 6 unit, then maybe look into selling your duplex and doing a 1031. 

However, these costs can often be added to your property's basis, which helps reduce capital gains tax when you sell the home.Once the property is officially a short-term rental, subsequent repairs and maintenance would likely qualify as deductible expenses. 

Perhaps you want to sell ownership interest.

So I would say that once she moves out we will probably sell our "forever home" and it will mean 10 years-ish is "forever" for us.

Unless you plan to sell one of these in the next 5 years, you'll probably get a better deal if you try to refi both of them at the same time.

It is solid to look at deals that are off-market and know that the ability to buy it at a price and either hold it or sell it will be coming with less competition on the purchase and more upside.  

If you can hold on till first part of January the showings and everything else should pickup.This would be my action items: 1. hire a new agent that can sell the place, and get you numbers are rent and selling and sell the place. 2. be honest on the numbers you can get on an ARV so that you can sell it 3. start to get the conversation started with a couple lenders on what these numbers on refi would look like for you and this property 4. my suggestion would be to refi/rent before selling at a loss because if numbers work you can hold for a couple years then sell, but this is dependent on your cash position and liquidity of your situation. 

“Selling” a co-living room is very different to showing a traditional unit. 

That also perhaps makes people more motivated to sell.  4-5 weeks....that's plenty of time to get a deal done.Good luck.

Quote from @Dina Schmid: You can sell anything you want, but that doesn't mean it will qualify for a home loan or be accepted by a building inspector.