Yes, it IS possible

barely. I managed to remove the pilot jets from a pair of premiers IN PLACE by removing the float bowls and using a long jeweler's screw driver. Have not tried replacing. As suspected they still had the 2 ring #17 pilots soon to be replaced with #19.
Has anyone seen any real advantage to the aluminum float needles?

No empirical evidence, but they do work well.

Having attempted to retrofit a pair of stay up floats to my A65 with brass needles, I can say that the aluminum does seem to work better with the stay ups

I have a set of ratchet box-end wrenches, the smallest of which accommodates screwdriver tips as used on power drills.

I use a phillips to do the bowl screws, and a long blade tip to extract low speed jets. Have done so for 20 years.

All of the new float needles I've seen for modern Triumphs and Japanese bikes in the last dozen years or so are aluminum.

perhaps using the alu needle with the stay up floats is the key. Otherwise I haven't seen a difference. Personally, I didn't have trouble with the old set up.