Mortgage for mixed-use with self-employed tax returns

[L L]

Hello-I am first time real estate buyer. I am looking for a mixed-use property. I am self-employed so my tax returns show a lower net income than what would normally be required for the mortgage I'm looking for. I plan on using the commercial space myself and also living in the building. There MAY be 1 or 2 additional apts for rental income.

My thought was that I should start beefing up my tax returns now in preparation for a mortgage in the future. My accountant says no- just save more cash for the down payment.
???

Ok I understand, but I cannot save enough to buy the building in cash. But would a large down payment (50%) make the banks less strict with the numbers?

Also, since I plan on using the commercial space myself and also living in the building, there would not be the full rental incomes the banks normally look at for an investment property. I was told (by a real estate investor) that I need to tell the bank that I am planning on renting all of these units out (and not living there or using them), in order to more easily get the mortgage. Is this realistic?? Or legal?

I'm a real newbie so any advice is really appreciated!!