Any guidance or referrals to professionals you trust would be greatly appreciated!

Readers should seek professional advice. 

My tax professional is stating that I would need an appraisal to show the lot/structure are valued at $400k if I try to claim $200k as a donation.

It could indicate they lack sufficient knowledge or experience in professional property management, which may lead to costly issues for you down the line.

Assuming your property is in Utah (like your profile indicates), here's the state law from a basic internet search:In Utah, a tenant who abandons a rental property without notice is liable for the lesser of the following: The rent remaining on the leaseThe rent plus the difference between the fair rental value and the agreed-upon rentThe cost to restore the property to its original conditionThe landlord can also remove the tenant's belongings and sell them if the tenant doesn't claim them within a reasonable time.

BP is a great place to connect and meet real estate investors and professionals.

Readers should seek professional advice.

A pool, a small gym, parking, internet. 

Assuming they are professional and skilled in the craft - alot of the issues you have faced, they will remediate and mitigate moving forward.

Did you work with any real estate professionals (agents, lenders, etc.) that you'd recommend to others?