Subsequently, after establishing a balanced relationship with the tenant, you can consider making upgrades to the landlord's apartment,as a sidenote: Should any usable items be removed during renovations, offering them to the tenant can foster goodwill and enhance the tenant-landlord relationship.

My husband and I househacked our apartment in Boston when we moved to NH during the pandemic and BRRR’d our second property (which balance a bit and hold/ STR).  

Too many people want a job with work/life balance, a house in the Hampton's, a Maybach, and the ability to binge watch Netflix every night and weekend. 

OR, if you're able to assume a low interest rate FHA or VA mortgage (but you need to have the difference in price vs the loan balance), that's an option too. 

$50k in equity - we would need to know balance vs. property value.

If it is tied to the home, you have a few options:1) include electricity in the rent (down side with that is tenants may be less diligent with electricity use and increase the bill)2) have the tenant pay it and include a copy of the statement every 1-2 months to show that it is paid in full.3) have the bill in your name and send a copy to the tenant each month (or whatever the billing cycle is) and they can add the balance to their rent each month. 

See Nobel prize winner and associate  quote....Gunner Myrdal, an architect of Sweden’s welfare state who was given the Nobel Prize in economics as the left-wing balance to his co-winner FA Hayek:  Myrdal stated, “Rent control has in certain Western countries constituted, maybe, the worst example of poor planning by governments lacking courage and vision.”3 His fellow Swedish economist (and socialist) Assar Lindbeck asserted, “In many cases rent control appears to be the most efficient technique presently known to destroy a city—except for bombing.”Seattle is a prime example.

And I'm hearing some commercial lenders require 30% of balance in their bank. 

If you choose a strategy such as this, make sure you don’t pay off low interest mortgage and then carry a higher interest HELOC balance.

All your question is answered in basic calculator.Your question is what's difference between 3 +5 and 2+7 ; they're all good product if used intelligently can be very profitable.Fact is , 30Y above 6% rate would not have significant difference in term of balance payment compare to 10Y I/O if you sell the house in year 5.Please do note that 10Y IO and 10Y ARM is vastly different.