Just watch out for HOA fees because they can be higher in boutique projects if they have a lot of amenities, not having an elevator will help here, and if one owner stops paying it can mean a lot to the other owners. 

Besides your rent, your cleaning fee should be the largest expenses for your normal operation.

Also, Baltimore has so many silly inspections, fees and fines they issue for little to no reason. 

They charge 15% reservation fee for a complete management or $150 monthly if you do place bookings and they do coordinate maintenance, inventory, cleanings, front desk, admin stuff, and etc. 

Rooming houses usually don't get to take advantage of sporting events, concerts, festivals that usually result in spikes in rental fees and more profits ( and glory) that AirBnb and other STRs get to.

Even the best managers charge a much lower rate, like a flat fee of $200 or maybe 25% of a month's rent.

You can see if the title company/escrow company will pay them an invoice for a consulting fee.

Usually the lender will charge an extension fee to keep the same rate.

Compare origination fee and rate mostly.  

Higher Fees and Costs: Cross collateral loans may come with additional fees, such as appraisal costs for each property involved, which can increase the overall cost of borrowing.In conclusion, while cross collateral loans can provide valuable opportunities for accessing larger amounts of financing and potential cost savings, they also come with considerable risks and complexities that borrowers must carefully consider.