Joint tax return?  

The seller may not want to do this, as many of these guys are benefiting from the tax deferral which comes with NOT moving title over.

(This is what we do, no upkeep,  and we love the 10% down, plus cash flow, principal deduction and tax write offs) Some of our investors use their SDIRA or 401(k) or pension to do this.4.

In my experience, these are also referred to as "QM" and "Non-QM" loans ("QM" = Qualifying Mortgage)And as consumer mortgages, these loans are generally issued under the person's name with the underwriting based primarily on the borrower's DTI (Debt to Income) ratio.

Will the property taxes skyrocket?

Cash flow is definitely the biggest challenge; both in terms of finding properties to buy that cash flow with a loan on them and just company wide given interest rates and labor/material is up and, at least where I'm at in Jackson County, MO, taxes are way up too. 

Conventional lending requires tax returns, good FICO and reasonable DTI. 

Quote from @Collin Hays: From a macro standpoint, cash flow is difficult when servicing debt, at least in the early years. 

We now live in Arizona and I frequently fly back to the southeast to repair or inspect the properties and already deduct the travel, lodging, and half of the meal expenses from my taxes. 

Forming an LLC for your rental property can offer liability protection, but no real tax benefit.