Dear Mr. Eckel,
There will likely be some controversy over whether or not your are an employee. To determine whether you are an employee will depend on several factors regarding how much control the company had over you (did they manager your day to day work, or were you free to work as you wanted). It sounds like they managed your day to day work if the company was trying to require you to stay on site and sleep in your truck. So, you are most likely classified as an employee under California law.
As this is the case, you can recover pay for the overtime you worked. To do this, you need to file a claim with the California Department of Industrial Relations. You need to file a form, which you can download at the following website: http://www.dir.ca.gov/dlse/Form1.pdf
You also need to contact the closest Division of Labor Standards Enforcement Office and talk to someone who will walk you through the filing process (this service is free). The office locations and contact information can be found at: http://www.dir.ca.gov/dlse/DistrictOffices.htm
When you talk to them, tell them: 1) you were an employee for the company; 2) you were being paid cash, 3) the company controlled the manner and method of your day to day work, 4) they worked you overtime and did not pay you, nor did they provide you with meal breaks. And you want compensation for this.
In regard to your truck, it is not likely that you will be able to recover from your employer for your truck. They have a defense against you for contributory negligence, and they likely did not owe you a legal duty in regard to the accident which caused the damage to your truck.
Good luck on the wage claim. Let me know if you need any further information.
Very truly yours,XXXXX