I'm concerned that the combined load of heat pumps and ancillary heat strips, along with other appliances, might exceed the 100-amp capacity during winter.As part of our future plans to add a third unit and separate the utilities, we intend to install two additional meters: one for common areas and one for the new unit.

With regards to MTR arbitrage, a quick definition may help less experienced investors follow this topic better.In this context, arbitrage refers to entering into a long-term lease with a property owner, and then furnishing the space (also probably setting up the utilities and Wi-Fi), with the purpose of renting it out at a higher rent for a profit.The value to the property owner is that if they enter into a lease with an honorable and responsible person, the rent will be paid every month on time and without fail (regardless of whether or not the MTR provider leased the space).

Instead, can you just cover the utilities or go to the laundromat.

I most definitely 2nd getting the utilities mapped first before digging.  

As I'm sure most of you know, a long-term rental is simple since the only recurring expense I own is the mortgage, whereas with a STR I'll own the mortgage, internet, utilities, furnishings, cleaning fees, etc. which just makes my projections a bit foggier.I'm looking for feedback on the below expenses and wondering what else I should be thinking about, that I don't currently have listed.

After utilizing the Do Not Call Registry for phone numbers, my list is cut in half, to about 3,000.

There are strategies that you can utilize here that can make it easier as well. 

I start with cleaning and repairs, then I apply it towards utilities, legal fees, late fees, and rent, usually in that order.I also have a holdover clause that says the tenant is charged 4x of the monthly rent, prorated daily if they hold onto the property after lease termination.

I've been getting a card or two a year to increase my limit (indirectly lowers utilization as well if you don't charge it up) - it does hurt the overall credit age though 

Did they have bank statements showing utility payments for the rentals?