I feel like if I exclude these buyers (at least in the price point) I will knock out a huge chunk of my buyer pool.

.…...if I am using a Self Directed 401K to purchase a multifamily unit, I know my income is excluded from taxation on a personal level but am I still subject to a business income tax? 

Another point is many municipalities also exclude multiple unrelated individuals from renting.

@Joseph ShaggsExamplePurchase property for $100,000You depreciate $20,000 over 10 years.You decide to sell it for $130,000Based on my understanding of the opportunity zone$30,000 of the gain would be excluded($130,000 - $100,000)$20,000 would be subject to depreciation recapture, max fed rate of 25%($100,000 - $80,000)

Exclude depreciation because it is non-cash.

If I sold the home now, I would be excluded unless it netted over $500k.  

. $13k loan at 3.9% over 60 months = $238.83/monthInsurance = ~$20/monthOverall cost per month (excluding gas) = ~$250I would be driving in my local area (Ventura county) but could also drive 45 minutes away into Los Angeles.

(You may also transfer property other than cash as an investment into a QOF, however a transfer of non cash property may result in only part of the investment being eligible for tax benefits)The Opportunity Zone tax benefits have been structured in a tiered approach as follows; if an investor retains an Opportunity Zone investment for at least 5 years, 10% of the initial investment is excluded from being taxed.

.: A 401k plan or an IRA that invests in a business (excluding real estate and venture capital business), assuming that the investment is in a pass-through entity like an LLC (taxed as partnership) or LP, could be subject to Unrelated Business Taxable Income/Loss.

Can you exclude $500K from taxes -- no, but you might get close.