Using 50% rule (with that HOA may be aggressive) depicts ~$200/month negative (so you may be worse than this).Now for the value add: $465k for $515k value implies a $50k value add

I almost all BRRRR deals, although I prefer the term value add since BRRRR implies that you will hit a grand slam every time.

Every state has an implied warranty of habitability.

If you have a history of neglecting on time payments, that implies disorganization or financial problems.

Month to month would tend to imply you can inform you are not going to renew next month but I don't know PA laws. 

That implies kicked out due to not following the lease, nonpayment, damage to their credit, possible legal involvement, etc. 

I've been running most of my side gigs anywhere from 2 years to 6 months (dog trainer, Beachbody coach, condition reporter for a property management company, manager for my mom's airbnb). 

Rents lag the property values which implies rents are very likely to increase at a high rate fir the next few years.  

Here in Michigan, the assessed value is 50% of market value.If something similar applies to this property, $90k assessed value would imply an estimate market value of $180k...

This would imply the tenants could keep the garage as long as they desire (or until you can terminate occupancy through one of the legal options)  Assuming that your duplex is exempt from the state wide rent control, the tenants have the right to the garage through the end of their lease (May 2022).  2 months prior to the lease being up, provide notice that the garage will not be included at the end of the current lease.