I have an Aviator Silver card that is my primary credit card that I am earning a lot of miles/LP on for most of my personal/family spending. I will soon be picking up a job with a company that will pay out 1099, no taxes withheld, etc., and will allow me to purchase a lot of things (new laptop, clothes, etc.) that will be tax exempt and contribute to my tax refund in addition to things like gas, food, etc., when I am on site in a different state doing this work. This will be ongoing for at least the next 5 years and possibly 10 or 20. My tax advisor is having me open a zero annual fee (effectively zero fee altogether the way I will use it) checking account to use only for things related to that business so that those charges can be separated out for tax filing and auditing purposes. I believe I could also use a credit card account in conjunction with that checking account for business related expenses. I would not want those charges mixed in on my Aviator Silver card. Ideally (I think?) I would have a zero annual fee or low annual fee credit card account with which to put all of those charges I can on that also earns me LP's and miles on the same AAdvantage account that my Aviator Silver is attached to.

One important detail - the company I will be working for will be doing all of the airline bookings (I can use AA, of course), hotel bookings, car rental, etc., and these will not be charged on any of my accounts.

From what I can see the two choices are to get a Citi card or get a second account with an Aviator account. Can I even have two Aviator accounts for the same AAdvantage member number? Any additional considerations if I do this?

I am already EXP with an Aviator Silver card and so outside of the Admirals Club access with the very expensive annual fee Citi Executive card I would not get any significant benefits by having an annual fee Citi card. If my tax advisor tells me I can write off that Citi Executive card annual fee as a business expense I will get it without question to access the lounges when I am traveling business or leisure, but would be surprised if that were the case. Otherwise, as zero annual fee cards go the MileUp card looks like the best bet since it is 1LP/dollar spent whereas the standard Aviator MasterCard is 0.5LP/dollar spent. Would I be able to get one of the business MasterCards from either bank given what I am doing with them? Would there be any reason to get one of those?