As PO BOX rates have more than doubled in the last 10 years, I'm trying to setup an additional mailbox for my fourplex building for the purpose of receiving administrative mail to effectively use it like a PO BOX.

To get the best rate, you will want to use a conventional mortgage so you can't put it in an LLC.

For those unfamiliar, these structures offer varying commission rates based on the sell price.

You get a 30yr loan on a fixed rate, the debt is paid by the tenants, while you still cash flow.

The year I bought the house the inflation rate was 9.1% (I didn't count that year as I didn't own the property for the full year.) 

I recently set up an LLC to manage and eventually take ownership of the property as soon as possible but I am assuming my lender will not allow that without refinancing with a higher down payment/interest rate.

Managing an STR a very hands-on 24/7 job if properly managed with a decent occupancy rate.

Tell me how often you have to file for an eviction.I didn't ask to negotiate the monthly fee, and never have since day one - as long as they provide me excellent service, I am happy to pay their requested rate. 

CAP rate (how many real actual dollars you put in your pocket every year) and wholesale (value of the property and wholesale value of the trailers). 

For long term I have less to manage but at the nightly rate and high occupancy the numbers sound way better.