Can possibly use the long term rents at 70%-75% no ratio . 

Can I use Solo 401(k) as source of funds to pay 25% down and leverage debt for remaining principal amount to purchase a duplex that I will owner occupy and rent the other unit?  

. - way too may issues renting, updates, policies, rules, repairs etc.

I'm struggling trying to figure out what the rent should be for something like that.

:Class A Properties:Cashflow vs Appreciation: Typically, 3-5 years for positive cashflow, but you get highest relative rent & value appreciation.Vacancy Est: Historically 10%, 5% the more recent norm.Tenant Pool: Majority will have FICO scores of 680+, zero evictions in last 7 years.Class B Properties:Cashflow vs Appreciation: Typically, decent amount of relative rent & value appreciation.Vacancy Est: Historically 10%, 5% should be applied only if proper research done to support.Tenant Pool: Majority will have FICO scores of 620-680, some blemishes, but should have no evictions in last 5 yearsClass C Properties:Cashflow vs Appreciation: Typically, high cashflow and at the lower end of relative rent & value appreciation.

Purchase price: $445,000 Cash invested: $22,000 Househacked and rented out all units

I bought it at auction, rehabbed it with my son, refinanced it and rented it out.

I know the area and knew it would rent for $1150(it did).

With this option you need to know the STR numbers of the area, and that the owner would have a significant increase of monthly rent.

True turn key rental with rents very close to market.