Normally the boot would be taxable but in this case it is covered by the primary exclusion.  

The intent of the law is to address the needs of homeowners by making the taxable value of their homes more predictable.

Your CPA is one of the many who apparently is not aware of this change introduced in 2009.In your case, 75% of the gain is excludable, and 25% is taxable.

@Andrew Linderer Unmarried individuals can exclude up to $250,000 in profit from the sale of their main home, and you can exclude $500,000 if you're married.So if you're single and you realize a $200,000 profit on the sale, you don't have to report any of it as taxable income because this is less than the $250,000 exclusion amount you're entitled to.

If the lender is unable to collect the remaining debt from you, there is a cancellation of debt of $8,000, which generally is taxable income to you."

Therefore, this child support is taxable income and is considered a common CIVIL debt dischargeable in bankruptcy.

Lets see what @Steven Hamilton II and @Bill Gulley have to say about this five generation non-taxable trust business.

This will offset the taxable net profits to the less than taxable level even if the property is paid off early.I also have capital reserves planned and have been working with a business banker with wells Fargo to set up my business account. 

@Dustin Keiswetter The $40K that you pull out would first be applied toward your taxable gain (if you qualified for the 1031 Exchange), so the 1031 Exchange in the facts provided above would not provide any benefit. 

If I factor the depreciation offset on my taxable income, I would actually exceed what I brought home from my W2 job .I get to work my own schedule, invest in my kids development, become a gourmet chef at home.Wohooo!