What kind of damage is there..... water damage, fire?

Normally tenants are only responsible for damage they specifically cause.

We can't drill the lock because there is no exterior access.We are responsible for calling locksmith etc. the constable just stands there to make sure there is no disturbance.While the swat battering ram sounds cool I feel like it will also go against the as little damage as possible thing.

And then the tenant will be so mad about the stress of it that she will be even more eager to sue you for damages.

I really fear more damage, utility bills, and theft. 

The hidden danger is that they get upset that they lost that paycheck, they are going to lose "their" house, and they damage it on the way out. 

I hate to make such associations and assumptions, but in my honest experience the guests that typically book my “bargain” nights tend to leave the home in poor condition or damage an item that they neglect to mention to me.

They get their original deposit + 2x the deposit as damages + legal fees paid (~$5K).

From what you have said you should be billing them immediately for any and all damage repairs, never take it out of their deposit, and if they hire a exterminator they pay not you.

The point of the deposit is to cover for damages ie. holes in walls, broken doors, damaged tiles, broken cabinets, etc.