I replaced my TOB and did the clutch while I was in there without draining the transmission. Bought this :
https://www.amazon.com/gp/product/B000P0U04G to keep the fluid in the trans after pulling the driveshaft. You do need to be careful and try to make sure that the tail stays inclined a bit so that it doesn't want to leak, but it's do-able.
It's sort of 6 one/half dozen the other. I didn't really have a good containers/etc to re-use the fluid, and like you had just swapped it. Leaving the transmission filled does add some complexity to the job though.