Hi Roth,
A tree service should be covered by business liability insurance, and its crew by workers compensation, which is incorporated into the liability policy. Business insurance does not require any sort of waiver. So to the best of my knowledge, whatever waiver you have doesn't apply to tree work professionals.
The recreational tree climbing waiver is intended to protect a tree climbing business from liability. For example, if TCI puts someone on rope and that person falls and breaks a leg, the waiver will (hopefully!) protect us from a lawsuit by the climber, and should help pay the climber's medical expenses. The liability waiver is not applicable to people who go out climbing on their own.
As for climbing in state parks, our suggestion is to try it. Trespass is not an issue because it's public space, and people can't be arrested for trespassing on park lands.
As far as I know, most state parks do not have rules against climbing trees; many rangers don't know anything about recreational tree climbing and have not seen it. If a park ranger comes up to you and asks what you're doing, be polite and explain; if they tell you to come down, do. Of course, always use cambium protection and a helmet, and tie safety knots. You can point out to anyone who asks that you are protecting yourself from injury and protecting the tree from damage by rope abrasion. Climb in an off-trail place where you won't disturb others who might be using the park and store your gear off trail. Let someone know where you are and when to expect you back; and finally, carry a charged cell phone in case you get into trouble (reception is usually better at the top of a tree).
I hope this is helpful.
patty jenkins