A Skeletal Soarwhale, preferably with increased strength somehow (Corpse Crafter?) can house quite a bit inside the skeleton. Put leather armor on it and it's fully covered. Put some Black Sand in it and it heals itself. Basically, it's a giant skeleton.
Note that the decanter thing would have easy to aim thrust, as it's small and you could basically use vectored thrust.
Another option is to use a chamber with permanent Reverse Gravity. Have an axle running along it so that it's half in the antigravity section, half in the normal section, and this axle should flare out like a giant cone, such that pulling the axle forward or back changes how much mass is getting rotated by gravity. At the end of this shaft is the propeller. You now have a gravity based propeller drive.
JaronK