They effectively said they would leave a bad review if we didn't fully refund their stay. 

Guest Damage Insurance...This type of insurance covers small damages (no more than several thousand) that guests might do to the property.

I think if you set up a brokerage account with the same bank that your business checking account for the LLC is at, you can simply move the money from the checking account into the brokerage account and then purchase something. like USFR, which pays 5.4% in T bills with zero risk of loss or BKN which pays 5.7% in tax free Municipal bonds if able to tolerate some risk (this gives me a >9% tax effective rate on my cash).

They can network effectively with placement agents - Agents are going to be the primary way a house is filled, so a reputable manager likely will have multiple agents who are willing to work with them already because they have a history of running good homes.

Damage is damage.

If not, she will eventually find a new place, stop paying rent, string you along, and then move out in the middle of the night leaving you with a vacancy, past due rent and most likely a mess and damage to the unit.  

Despite these challenges, the successful sale at $87,000 highlighted the importance of strategic planning, effective project management, and strong partnerships in maximizing profitability in real estate investments with Partner Driven.

Given that it's almost a 50% increase from the existing rent price, you might want to set a timeline of 2 or 3 months before it taking effect so they can find alternative housing if they plan on vacating instead of staying at that price point.Another option could be to ask for the rent increase, but offer something in return.

-As to rent payment, in Florida, a tenant would either owe liquidated damages (as stated in the lease or would owe rent that accrues during the lease term until such time as the landlord is able to re-rent the property on their account.

Direct negotiations with sellers can be effective in getting you a good price but make sure you have a strong understanding of the market.