Do you need a power tool?

I've cut up a lot of small trees with just a hand saw, especially when they're green and soft.

Now that you can reach most of it, just get a ladder and a saw and start trimming.

It takes a long time and your time may be worth something. But on the other hand you're unlikely to hurt yourself with a handsaw, and that may not be true with a chain saw.

Oh, and really pay attention to that spring back thing. A friend of mine broke his back when he sawed off a limb end, and the rest of it jumped up when it was freed of the weight. Hit his ladder and knocked him off.