Just my opinion and what I would do in your shoes...
I would not close in on any face fragile fish that has known to die after a hard slam to the money maker. I would slowly move in on him after the tank is half empty/full.
2nd, I would get 1-2 Sponge filters running now in your tank/sump to get ready for this day. When the day comes, dump the Sponge filters in... BB and o2 is a plus and you can take your time and leave him in there for 1 day plus (better to be safe than sorry) and add heater if needed, done deal.
I would also place a tarp or something big and clean under the temp tank incase he jumps from the box/net and he would likely land on something dust/particle free to keep his sexy scales/eye/blah blah...
again, just my opinion and things I have thought of from experience (sometimes its better to over think than under think

).
G/L and take pics/vids of the move