A non-involved banker friend told me that the noncompliance was overly conservative if it was based on the relatively small amount of money I transferred.

VA, Non-QM, Portfolio, HELOC and multi-family and/or commercial mortgage banker under one roof

Back in the 1970s when I first entered the real estate profession (my fellow bankers were shocked that I left international banking to work as a COMMISSIONED commercial real estate salesperson!)

In this post type of concern  I ask my circle of influence (bankers, insurance, contractors, fellow storage owners) their perspective on the economy and also their sphere of influence.  

Go to local real estate presentations / events / awards (maybe you have a local annual NAIOP awards or a BISNOW breakfast). 

So, is it worth risking $300 to file for the mechanics lien and then also take time off for the hearing etc with a 50% chance of being awarded $300 for the work and $300 for the court filing fees?

It can happen but you need to have a seasoned Banker or Loan officer with very lien ant construction underwriters.You will need a solid and very descriptive "LOE" letter of explanation and make sure you’re not trying to build a 2-4 unit or a smaller home versus the current homes GLA/SQFT or it will "Not" get approved.

Speak with a commercial banker in the region that your property is located. 

Buying property for “materials” - back in the late 1970s I was a banker in Geneva, Switzerland.

I was a banker for many, many years with both big and community banks.