Well, after 23 years, I succumbed to the "mass hysteria" and got a BP/W. . . . In a single tank configuration, where are you placing "stuff"? Such as a light (though maybe its on a light sock), SMB/finger spool, etc.
Good question, and my reply may simply will echo many of the suggestions you have already received. To a great extent, a lot of what people do is personal preference, seasoned by a large dash of habit. So, I am not sure there is a right or wrong.
The stuff I carry generally includes: a) lights primary and back-up, b) writing materials, c) DSMB / lift bag, d) cutting tools, and e) signaling devices. The specific equipment list may vary somewhat according to dive site and type (day vs night, quarry vs ocean, etc). I have pockets sewn and glued on both thighs of my DS and my WS. The left side is a larger bellows pocket and the right side is a flat pocket. In the left pocket I keep my spool, whistle/mirror, a second back-up light when I carry one or a back-up mask, and a secondary cutting tool. On the right side I keep my Wet Notes equivalent (Halcyon Divers Notebook). My primary back-up light is bolt snapped to my right chest D-ring and held down with a piece of inner tube. I wear a wrist slate, wrist-mounted computer, wrist-mounted compass.
My DSMB (6ft) is attached to the bottom / base of my BP, held in place with two bungee loops. I also carry a lift bag, slipped into a Dive Rite sleeve which is attached (inverted) on the lower left side of the plate with a couple of pear clips. I have a double ender attached to the end ring of the bag, and also to the plate, so I can reach down, unclip the double ender from the plate, and pull the bag down and out of the sleeve. Canister light is attached on the lower right side of the plate, inverted, so all I need to do to turn it on is reach down and find the switch on the bottom of the canister (I keep it on the right side because I have the light head on my right hand).
Cutting tools are shears carried in a holster placed on the right waist strap, behind the D-ring (to which a wreck reel - when used - is clipped), and a small (1) folding Buck knife carried in the bellows pocket, attached to a double ender.
I usually do not carry a back-up mask. When I do, I put it in the left bellows pocket, and take out the secondary back-up light.
I have tried wearing a Dive Rite thigh pocket attached to my waist strap and my thigh do not care for it. I have also carried a Halcyon waist strap pocket (hard-backed) on the right side, which I found cluttered my waist strap too much.