I also noticed that it would be to heavy to move it on the head, but a friend of mine always thought that these pallets extruders create a small tube like filament witch is pushed into the head. I told him that its not working this way.
But a day later is ask myself, why not extruding the filament with a big cheap machine, and then the filament runs right through a feeder.
So basically you don't have a spool, since the pallets extruder just extrude as much, as the feeder needs.
It could work, but it will also be big and heavy.