I only have personal knowledge in CA and OR, but in both of those an umbrella rider will not cover business activity.
On a few occasions I have used my machine to load something heavy from a neighbor's place into a truck or onto a flat bed. Usually I will be offered a small amount of money after the job is complete.
Even though the job is finished and there is no danger of an accident or an insurance claim, I always turn it down because I have insurance that covers me if I am doing a non-commercial favor for someone, but does not cover any commercial activity.
Sure, an extra $20 would get me a few gallons of diesel, but it isn't worth having an insurance company wiggle out of a legitimate claim over.
I'm with Dave on this one, it's the same here in Canada. I'm insured for liability and comprehensive coverage through my auto policy, homeowners policy won't cover over 25 HP here, at least not my company. And that's only while traveling on road with the tractor, doesn't provide any liability for commercial use. What I do have is an additional endorsement that gives me coverage while snowploughing, but has a $2500 deductible. Essentially, if I rip the side of someone's house off while doing them a favour, as Dave does, the insurance company will cover the damage after I eat the first $2500. If they get even a sniff that I was being paid to do it, I suspect I'm out of luck.
What I suggest to someone that wants to pay me for helping them out, is that I drink beer, and an extra dozen won't go astray
Or, a gift certificate to a nice restaurant at Christmas time, things like that. You don't want cash changing hands without commercial insurance coverage is the way I see it, not good news for you.
One other way to look at it, if you get something other than money in exchange, it's one thing you won't have to pay for out of pocket. So, you need clients that are dentists, grocers, auto mechanics, etc.
My 2 cents,
Chilly