Looking for pointers from anyone who has successfully appealed an apartment complex property tax assessment.

You need to work on reading comprehension.  

- what if there is a tax assessment? 

Do not trust the the tax assessed value.

@David Begley, it's very relative in terms of assessment.

Since a triplex is a small multi family unit and falls under residential lending, how does one go about assessing the ARV when it comes to figuring out what number to use for refinancing?

Also, make sure you review the budget/ledger for the HOA to make sure there are not any major assessments coming in the near future.  

It will rent for $1200-1300, but has an HOA of $100/mo and relatively high taxes due to special assessments.

@Chris Heeren The landlord has a right to withhold a security deposit for any of several reasons, such as if the tenant:damaged the premises beyond ordinary wear and tear;caused waste or neglect of the premises (such as leaving hot water running in the bathtub for days);didn't pay rent;didn't pay for utility services, whether the landlord provided these or the tenant paid the utility companies directly; ordidn't pay mobile home parking fees that the local government assessed against the tenant.

I'd suggest if there is anyone who can assess a construction rehab or new project and being closer to actual it certainly won't be the investor type, it would be an experienced lender who has about a 1000 more times the experience.