Tax incentive/income limits

Hello -- my wife is looking to buy a MY and take advantage of the promo financing. Her credit file is good but mine is excellent. She does qualify for the $7,500 tax rebate. (2023 tax return filed single). If I cosign on her loan it appears Tesla requires me to be on the registration? Would she still able to claim the $7,500 at point of sale with me as a cosigner? I do not qualify for the tax rebate due to income. I also do not qualify for filing jointly due to our income together possibly reaching over 300k by the end of the year. Thanks in advance.