Excuse the 2 penneth input - but why not have the hammerhead of the tomahawk shaped to make the adze part? Then you won't need to remove the head each time you need it. If you need the hammer part then, in a push, you could use the side of the head.
Just a thought.
I'm in the process of restoring a pile of tomahawk axe heads, both fixed headed and take-down ones for eventual sale here and at the Moot. So if you're interested in getting one of those converted as I've described above then drop me a PM. No pressure, just a suggestion is all.