Lets get off that idea. Several factors pop up right away:
*You absolutly need the best restraint system that you can install.
*The crushable space in front of the cockpit sometimes contains a fuel tank. This will certainly rupture on impact. Count on the fuel to spray an ignitable mist on the hot engine.
*Trees may penetrate the windshield before impact.
On the other hand, helo pilots are taught to execute an extreme flair in the event of engine failure. Plan on going into the trees tail first. I flew with a guy that did this in Alaska in tall trees. He reported no injuries. The USAF Sikorsky was totaled.