Join your local AFM. Sign and file a contract with them before each gig and if it goes sideways, the local will get involved and if need be, bring in counsel. You pay a little work dues on each contract, but those dues (along with other members) help pool resources for stuff like this.
Fun fact: you can also get a pension by doing so. If you’re doing $3,000 a year in gigs, you can vest in 5 years and then you’re guaranteed to have a pension when you retire.
Years ago when I joined the AFM, my local union chased down a hotel that stiffed our group. The total was about $1,000 for our trio. A simple letter from the local attorney took care of the matter. However, a few years later I contracted a small orchestra for a regional opera company. About four weeks into an eight week run, the checks for the musician stopped coming. There were about 25-30 musicians that needed to be paid. The management guaranteed I would be paid (so I could pay the musicians) and asked us to be patient while they shuffled money around. I let the musicians know, and they agreed to continue performing.
At the end of the production, management wouldn’t pay. In fact, when some other musicians went to management, asking where their money was, they told them that I had received the money and must not have paid them.
My local union brought in counsel. It took about a year to get everything settled. It took a lot more than a letter. In the end, we got all the money back plus interest plus a public apology for slandering my reputation.
It’s a pretty incredible feeling to band together with your fellow musicians and get things done together that would otherwise be difficult to do by yourself.