There’s something that doesn’t add up about this, if he doing all those miles, towing a trailer for hire and reward it should have a tacho fitted and come under drivers hours regs, so if he has 2 week’s holiday and 5 days Xmas & New year, excluding bank holiday’s, never mind all the downtime fitting engines and parts, is over 2000 miles a week, at an average speed of 30 mph is 68 hours driving over 5 days, which is illegal, you can drive 9 hours a day, and can do 10 hours twice a week, maximum 56 hours a week, but must not exceed 90 hours in any 2 consecutive weeks, sounds like a dodgy set up to me, bet he doesn’t take statutory breaks either