My custodian does not have a money market or similar sweep account to keep idle cash earning.

Just remember anyone who has acted as your employee, attorney, accountant, investment banker or broker, or real estate agent or broker within the 2-year period ending on the date of the transfer of the first of the relinquished properties is considered your agent and is disqualified from being your QI.So definitely ask them for recommendations but they cannot act as your QI on the exchange. 

Things like a website, an email at your domain and credible social accounts (even small things like a profile pic and bio) can show you are a legitimate business.

I have cash reserves and money in retirement accounts, but I don’t want to dip too deeply into my reserves.

Getting a bit overwhelmed with all the required County Level and City Level business licenses, STR permits and Tax accounts (Business Tax, Franchise & Excise Tax, Sales & Use Tax) to register with the state.

You will also need to have a US Bank account.  

It forces me to call VRBO to reset the account but luckily they are easy to get a hold of and fix.  

Future land appreciation in this area might outweigh any tax benefits from buying in other areas, with a better (tax-wise) ratio.Before pursuing your plan, talk to a real estate accountant to figure out if you can, in fact, benefit from cost segregation.

Ensure you account for expenses like maintenance, vacancy, or capital expenditures.

. - I have been saving ALL of my cashflow into its own account to accumulate to buy the next rental (totaling ~$24,000).