Establish a bank account for each property; giving the address on each
checking account, also the checks will be your mail address. Bring
this into an accounting software like Intuit and see your tax man and
your head doctor with that many headaches.

I just have one account for multiple properties - just note on the journal
which is for what. I have even purchased common things like office supplies,
repair material, landscape goods, etc. and don't even note which is for what
but just divided it equally amongst the properties. Done this for many
years, no headaches and no complains from the IRS so far.

The headaches comes from doing what if games on the spreadsheet as to put
what expenses where and on which forms to achieve the minimum tax payment on
the afternoon of April 15. But I have so much deprecation now that no matter
how I do the returns, I still pay no tax. Actually, I rather pay huge taxes
and have a huge cash flow.