Has anyone directly reached out to the major carriers about having a cell tower built or added onto one of their properties? 

My insurance carrier calls it a "Fire" policy, but the idea is the same.

Although the loan documents definitely do not require earthquake insurance, the note holder is using a vague "weasel clause" that says "Borrower shall keep the improvements now existing or hereafter erected on the Property insured by carriers at all times satisfactory to Lender against loss by fire, hazards included within the term "extended coverage", rent loss and such other hazards, casualties, liabilities and contingencies as Lender shall require and in such amounts and for such periods as Lender shall require."

If you're concerned about claims, take a look at the top 5 carriers for claims handling for your type of risk. 

Long story short, I am wondering if there are any blanket recommendations for commercial insurance carriers as my goal is to establish a relationship, 1031 into larger properties in the coming years, and I'm open to transferring all my other business to them if they are competitive with my current provider. 

Though it is a bit more I had to eventually start working with an insurance broker so they could help identify carriers everytime I ran into an issue with an existing carrier. 

I say shouldn’t, because some carriers or agencies are not well versed in rental properties and rehab properties.

I would still check it in case one of your carriers turns out the best.Sometimes, if the price is close to bundle, it may make your billing easier in terms of the amount of checks you write.

Anyone know of what other carriers I can try to get comparable coverage and reasonable rates? 

A lot of them exclude short term rentals so make sure you are upfront with your carrier and they have a policy for you.