The key word is reasonable, not beneficial. Plus, the IRS example stated flatly that this was the precedure to follow. Plus what Critter said. You care aboutr doing this correctly, or else you would not be asking the question in the first place. My personal criteria when I am in a dilemma regarding the right route if how comfortable I would be explaining my position to the IRS.
In regards to the roomate situation, again, the key is are you renting for Fair Rental Value. Here is a good link that show how the roomate situation might work: https://ttlc.intuit.com/community/tax-credits-deductions/discussion/if-you-are-not-renting-a-portion...
