It might be time to have a firm conversation with the tenant, letting them know that going forward, rent needs to be paid in full on the due date as stated in the lease.

Has anyone else had this problem, I've removed the baseboards and tapped it back together once already but it continues to separate, not really sure what to do, it looks great and holds up super well, except for the gaps! 

Our local organizations do a lot - we have representatives meeting with council members, a professional PR firm to help change the narrative on STR's here on the islands, and we're working towards increasing our own lobbying power.

In the second drawing, I had removed some portion of that wall.

Add another $20 a month for that.Add in HOA fees ($300 a month; shown in your link), Gas, electricity, high-speed internet, water, trash and snow removal. 

- Any recommendations on how to vet CPAs and cost segregation firms?

The top ones we see in our bookkeeping firm and that I've experienced personally doing BRRRR's are overleveraging and romanticizing the cash flow. 

There is a time and place to be lenient and forgiving on things within a lease, when someone is not respecting something big like this, you have to unfortunately be firm. 

Demolition and Removal: Outline areas to be gutted or removed (walls, flooring, fixtures, etc.). 

If you ask the manager to justify a fee and he starts hemming and hawing, move on or require them to remove the fee.