If you are going to be a 'contract climber' then that makes you self employed as per IRS rules as you are making your services available to multiple companies on your terms and to a certain extent at your convienence. This means that the companies should send you a 1099 and you will be able to deduct expenses for travel, equipment, a portion of your meals, etc.
Depending on what your home state is, workmans comp normally will not cover the business owner, but the companies that hire you may need to pay WC on you. I think you should look into Disability Insurance in your case.
As I understand your plan, you are thinking the homeowner will be hireing you separately from the main contractor. I'm not sure they or you will really want to do that. If the main contractor is working the porty and screws up causing a big limb to crash through the roof, who is a fault ? The MC blames you and as the homeowner has made a seperate deal with you, the homeowner may not have a good case against them ? You blame the MC for screwing up and again the homeowner is caught in the middle. A bad scene all the way around.
When I contract a climber, HE/SHE WORKS FOR ME for that job. I own the jobsite and it is my insurance that is covering things. I also tend to have a rule here that the climber calls the shots on how he rigs and makes his cuts. I tend towards the careful side so if there is any disagreement between me and the climber it will be because I want things done slower and safer.
Rick