We've already been preapproved to put 3.5% down on a conforming loan for a primary residence.That's the context, and my question is ultimately: What are some legal and tax efficient and effective methods that could be recommended to look into for using the liquidity in the business account to cover our down payment and closing costs? 

Ladders or even non conforming stairs could be insured but dealing with the lawsuit should it come probably isn’t worth it.

If your circumstances don't confirm with and fit in a conforming box then contact a alternative lender for other investment funding options.

Try and stick with portfolio lenders, if possible, since they don't have to conform to Fannie/Freddie guidelines.

@Shelley Wenk a conventional mortgage can be conforming or non-conforming.

First, your primary home was probably what is termed a conforming loan.

And doesn’t actually understand the difference between illegal and non-conforming.

At least not on a conforming mortgage.

You should also look into refinancing out of the FHA loan into a conforming loan after 6 months of ownership.FHA loans have MIP, which is pretty expensive and effectively increases your interest rate.If you can buy wisely and ride the wave of appreciation, you could have 10% equity in the property fairly quickly and save some money with a lower effective interest rate, even though you will have PMI instead of MIP.If you can get to 20% equity, you can get rid of MIP/PMI altogether.Of course, rising interest rates will affect any refinance strategy.Also, if you refinance, already being told by your company in writing you are being transferred, then you may be exposing yourself to potential federal mortgage fraud issues, by knowingly violating the 12-month owner-occupancy requirement of the mortgage.

This just means I can't rebuild as a plex if it burns down, but is grandfathered as 'legal non-conforming' now.