My experience has been that its usually a person that has the mindset , "Ima gonna get paid!" and will expect you play along but for free and in the end there really is no money coming from nowhere for anything but to clean it up. If it does the money will go into the homeowners pocket.
Dealing larger scale you can expect to get paid but you have to know what you are talking about. Like how you came up with the price. Best thing to do is to give a price to remove the remaining tree and replace with nursery stock. In many cases the homeowner blows it out of shape trying to make money on this deal and you end getting nothing, not even the work.
Sooooo... whose up for providing free estimates? Whose dumbass idea was that anyway? Everytime I write for ins I tried hard to make sure I get money for it, I might be sneaky but if I know and they don't why should I? I have told some people I am not going to write a free estimate for their insurance company. Sometimes the job is so complicated I feel I want money.
If you are still going to do this then I would look for a private appraiser either you or the client can hire. They are easy to find in general and you can fill in the blanks. I would just tell the client to call their own private appraiser who should be able to handle the BS involved while you do your thing and then get on with the rest of your day. A private appraiser should be able to handle pricing out trees or at least be very willing to muck it through and make his money. And I guess he should after what he's gotta put up with.