Sorry can’t help with a picture (my Hydros is back in Egypt, I rarely use it now but I keep as a spare it If I wanna dive with friends);
I bungee my SMB between the bladder and the soft backplate using 2 of these (I got a 30pack from Amazon for like 20; the ball is just a guide to finding it by hand vs the bladder bungee —you can easily just do bungee without the ball thingy)
I basically thread them though the “backplate” kind of kidney level and tuck the SMB there predive; and forget about it till I need to deploy - reach with arm, tug free, use
Once at surface I had rolled it back, and hang on Dring till I’m out (as it’s not easy to place the SMB back there with the BC on)
When I switched to the crotch strap harness I would reattach the SMB there rather than a shoulder Dring
Spool is part of the SMB “roll”, on the inside
For shoulder Dring located stuff (torches, spare boltsnaps) I use inner tube sections to keep them trimmed and not dangle
I used the ninja and thigh pocket; disliked both (they tighten motion at my hip joint due to length) and switched to tec shorts for real storage (GoPro, notes, line cutter, spare mask, primary light)