Just make sure you are saving towards those slow months during the peak months, buy a deal at the right price (don't overpay just because its a turnkey STR or you think it will make more money than projected), and look into ways to increase bookings during those slow months with some marketing and operation tweaks. 

I am wondering if transferring the cash periodically to a standard brokerage IRA account may be my best option.

-----------------------------------------------------------------------------------------------------------Recommend you first figure out the property Class you want to invest in, THEN figure out the corresponding location to invest in.Property Class will typically dictate the Class of tenant you get, which greatly IMPACTS rental income stability and property maintenance/damage by tenants.If you apply Class A assumptions to a Class B or C purchase, your expectations won’t be met and it may be a financial disaster.If you buy/renovate a property in Class D area to Class A standards, what quality of tenant will you get?

Because here, the proposal would increase property taxes about 5x.  

Materials have increased more than 20% in the last 5-8 years.

But once I got the bills, I increased the rent with the tenant's approval and signed an addendum to the lease stating the rent increase would be X and the owner would take over utilities.

At annual rent increases, I do scour Zillow for market rents in the area, which I share with my tenants.

Rents have increased significantly but so have housing prices. 

The importance of lowering expenses and increasing efficiency to maximize property income.

And over time, as those assets to make our product we sell had a fixed price, the dollar does not sit fixed, our cost of product increases meaning increased cash-flow.