I have a renter in there now and am wondering if a cost-seg makes sense to do financially as I am planning to keep the place for 10+ years. 

That had even a passing resemblance to tax returns or financial statements4.

Financial advisors focus on what they now best.

Also, the whole point of hiring a PM is to handle tenant, maintenance, and rent collection, so if your partner isn’t actively managing but just supervising the PM, IMO not worth having a two people essentially looking over the same tasks.Contributing financially for one person and the other having no financial stake raises decision making questions, such as when to sell, how profits will be distributed, etc.

And financial experts are asking me if the question is a joke?

Quote from @Stuart Udis: ....But I set the goal of acquiring 50 doors in the next 3 years using the BRRRR method and will then be financially free...isn't that a scalable business :)We see the above type comments from not so experienced investors or business owners all the time being posted on BP.  

But everyone has their own unique financial situation, financial goals and risk tolerance.

You could see an attorney or even better talk about it with your financial planner many have legal tech now that makes it essentially frictionless to get your estate work done and keep it updated.  

Your taxes are none of the ex wife's business and this would seem to address your concerns.I would also put her on notice that future requests for financial discovery will be two-way and if a discrepancy is seen in the other direction you will seek support from her.

I think real estate is very forgiving (1) over the LONG term and (2) if you're well capitalized / in a strong financial position.