The full metal jacket shafts would work, but you would need a high speed saw to cut them being they have a carbon shaft inside the aluminum shaft. Easton also make the ACC Shafts which are opposite, carbon outer shaft with aluminum core shaft. You can use a dremel tool to cut either since your not worried about getting them square.
Some additional info about the numbers on aluminum shafts. Sizes are identified with 4 numbers printed on the shaft such as 1816. This means the arrow has an outside diameter of 18/64" and a wall thickness of 20 one thousands of an inch.
Carbon arrows normally use a measurement of the spine. Some use 3 digits like 300, 400, and so on. 300 bending, or stiffer/thicker than 400. Some use 4 digits, Gold Tip does this. You will see something like 7595, if i remember correctly this just means the arrow is made to handle 75-95 pounds of draw weight. That's it in a nutshell without getting into to much detail if I haven't already.
Carbon arrows used as toggles would take a little more care to keep them from splintering. First you need to make sure you get a nice clean cut. Next, even with a nice clean cut the potential for splintering will always be there if the ends come in contact with a hard object like rocks and such, so reinforcing the ends with something like epoxy or something would help prevent this. You could always get some arrow inserts and epoxy them into both ends of the carbon toggle, but this gets the weight up as most inserts are about an inch long.
Now, if I haven't said enough already. Some arrow manufactures produce small diameter shafts which use an outsert instead of an insert to hold tips. These carbon arrows having a smaller outside diameter and have a much thicker wall. If I was to use carbon shafts as toggles this would be my choice because it would take much more force to crush them. They would also be tougher to splinter. I just happen to have a couple that I no longer use I may just try.
And that is a little arrow tech for today.