I see absurd maintenance/cap ex numbers from a majority of RE investors (even those with modest experience).  

Not sure there is a BEST , however I just got 875 for a 2 br all in 60k, and 850 for 1 br in ,my apartment building in East Cleveland, so 20% net caps pretty good

I would also say that there needs to be a cap on the first with regard to rehab draws.

The 50% LTV restriction was an older rule back 5 years in 2016, now in 2021 if you were to do a SUB2 and wanted to refinance then you'd be allowed to do a rate term refinance 1 day after you purchase your property via SUB2 or cash out after 6 months on title up to the LTV caps that your occupancy allows (investment, 2nd home, or primary).The issues comes when you try to complete the refinance and the underwriter typically wants 12 months of mortgage ratings (payment history) on all mortgages on your name or on the property you're trying to refinance.

My building also puts a cap limit of 30% for properties that can be rented out.

If scaling is your priority I would be open to location, buy on cap rate, and use the 5% down program to move every year. 

You're missing one factor: That you can sell your property and probably not pay capital gains since you've lived in the property for 2 our of the last 5 years.I'd split, sell and take the money (or most of it) cap gains free.

Oregon has capped rent increases at 7% + CPI (10%) max for future reference as well. 

In BC, we have caps on rent increases and they are usually well below 5%. 

You will have basically no cap ex or maintenance expense and will be able to raise rents by the time any of these expenses start.