There are so many rentals in the area, probably on shared wells, so those people have either decided the STR use is okay or they are comfortable risking it.My intuition is that any actual disagreement over water usage could be handled with the other owner; but the risk would be if the other owner just doesn't like the STR and wants to use the well agreement as a reason to demand it be shut down.Any advice would be greatly appreciated!

Ensure the STR’s projected income comfortably covers new debt, even with conservative occupancy rates, and maintain reserves for market changes or vacancies.

It all comes down to picking the right areas that work well with your personality and attract the type of clientele you feel comfortable working with. 

And unless you have very deep pockets, you can't afford to be that much off....So as has been said....hire a very experienced General Contractor and have them give you a budget number based on your SOW, (plus they will find other things that need to be done that you will not have seen).On your succeeding projects, you do a budget yourseld first, then hire the GC and compare numbers.Then, eventually you will be comfortable going all solo...but it takes time.

Once you’re comfortable, focus on creating content that reflects your business’s unique personality and values.If editing and creating thumbnails feels like too much, hiring someone on platforms like Fiverr or Upwork can save you time.

Or they need to move to a cheaper city / state where they comfortably afford.

In short, if you’re comfortable relocating one of the sides to move in, and comfortable to live in the place, than just do it.

It all comes down to your comfort with risk and how fast you want to grow.

I'm more comfortable working within those parameters than others. 

You should screen everyone the same, but still, it's a bit of a comfort knowing FF is mostly all working professionals.