Go off the loop to inflate the bag…. Sorry, that’s just plain crazy when there’s perfectly good inflator hoses to do the job. Even use a gas nozzle to inflate a open bottom bag.Maybe things are different in the UK. Everyone I know personally was required to shoot an smb in ccr class using a closed bag orally inflated. It really is not hard at all, it’s not risky or dangerous. The idea that’s it’s dangerous to orally inflate a bag on ccr is puzzling to me. As has been stated by several people it isn’t hard.
To your point of having enough breath to clear the loop: take a breath from the bov or your bailout. Or even better, be intelligent enough to not use every single last ounce of breath you have. In a lot of your posts you really seem to think the most basic things are dangerous, hard to do, or risky.
End of dive, reach back for reel, pull off bungee loop holding bag to reel. Tighten reel. Undo SMB loop, hold reel in left hand, look around, tug string for gas release. Done. Start ascending. 10 seconds?
If using an SMB it must be deployed from the wreck as you’ll drift. Plenty of skippers have shouted at those that disobey this rule. One bag per diver is more normal as the skipper needs to count the bags before pulling up the shot line. It is common to drift miles downstream of the wreck if there’s a long decompression obligation.