Advice hollowing out a slit drum

As recommended by MadDogMike I have posted this here. - Thanks

I am a beginner at carving and I do not have any one around to show me what I'm doing. I am carving a toere drum. I have the slit carved 18' long and 2' wide over half way through the drum already (about 5' deep).
Now the problem.
How do you carve the interior hollow using only the slit for access?
Any advice would be great.
I have only started to carve, did a wood fish hook from koa and now starting both the toere and tradition pahu drum.
Big ambition.

So far this drum looks clean and sharp.

JohnnyP might be your guy check out his stuff
he is on page 2 as of this post. Im sure he will pop in soon and
would set you right.

Use a chainsaw... watch this video

helped me big time
http://www.museum.hawaii.edu/exhibits/taurima/Etua.mov

^^Wow, what a fascinating video!^^ Well worth watching.

I love watching and listening to old school Island carvers.

Peter, I made a slit drum too, and this video about summs it up.
Be careful to not make the wall too thin right next to the slit
like I did. It has already begun to crack.

What kind of wood are you using ?

Looks like a good start on the drum. Unfortunately, that vid is not working this morning. Bummer, I would like to see it too. Maybe it will come back. :(

Just watched the Excellent Video, Might need an Apple plug-in. well worth the effort to get it up.
Slow and steady with the chainsaw and you can use a Long bent gouge to finish inside. You can Also use a torch, but Very carefully!
Excellent start though!