Once you drop it, the way to make it so you can change the fluid easier is to choose one of the bottom bolts and drill through the housing to intersect the bolt hole from inside.
That way to drain it you just pull that bolt, then put a little sealer on the bolt threads when you reinstall it.
Alternate, but takes a bit more effort is to punch a hole in the arm, then tap to take a pipe plug. best way to punch the hole is to drill a smaller hole, then use a punch to roll the edge of it so it's wide enough to take threads. (arm isn't thick enough to thread without rolling a shoulder) You may be able to use a rubber plug in a drilled hole. Either way make sure it's in a spot that clears everything inside.
Don't know how well tapping the carrier housing would work, steel to aluminum gets kind of finicky sometimes.
Don't recommend doing it while installed.
ken.