We could use a new cleaning company though.  

On another note, I am vigorously researching construction methods for the new house, and also chipping away at some concept drawings for it.

Since you aren't looking at the BRRR method, I am assuming you want something that is turnkey.

It is a freehold property, recently renovated from top to toe with high quality, large garden, and kept very clean at all times.

Whether it’s the proper legal route or unconventional methods, I’m open to any suggestions to help me get rid of these tenants sooner.Thank you in advance.I completely understand your frustration—situations like these can be incredibly challenging, both financially and emotionally.

These days as you mention with STR almost everything can be handled remotely...cleaning, painting, locksmith, yard care, even drive by pictures of the house occasionally or internal pictures too. 

What methods are you considering doing?

More traps, patch up holes, tell your tenants to be extra clean when dealing with food. 

To set the stage, I'm owner of a short-term rental property in the Poconos in PA and we use a property management company for bookings, maintenance/cleaning, guest management, etc.This past weekend we had a guest booking but when the guests arrived Friday evening the house had no running water, though it had been running fine earlier in the day when the Property manager (PM) was at the house to give a final check and leave the welcome packet.

You'll likely want someone that can handle A to Z with marketing, pricing, cleaning, maintanence, decor, websites, reviews etc.