I’d do the improvement.

Without a good deal you can’t buy anything.Not sure what you mean by joint ventures specifically though

We keep track of property expenses - all maintenance expenses, improvements, and business expenses, as allowed in the tax code (like a subscription to Wall Street Journal and lunch with other investors). 

Another one does joint ventures in small/medium multifamily, another one is going solo on small multifamily.

I am joint owner of the property, but she is the only one on the mortgage.

Even if they play hard ball, from your numbers above, you'd make about a 30% return on the improvements- that's not bad when coupled with good cash flow. 

Use that as a template and improve as needed:)https://www.biggerpockets.com/...

It can only be deducted if used on the same subject property for capital improvements, which you say you don't plan. 

I can sum up my experience by saying, you get what you put in.Coaches help you devise action plans, improve on your weaknesses and establish accountability measures.

I like to listen to others' stories (good/bad/ugly) and learn ways to improve whether it's from their mistakes or our own mistakes.