A backplate and wing (BP/W) may well be the best solution, also for single tank diving, for people whose frame isn't average (eg very tall, or overweight/obese). Maybe that's one reason they are so popular in some areas
.
As far as I know, most traditional BCDs (either jacket style or back-inflate) tend to have a "one size fits all" plastic backpack that is often too small for tall people (I am 6'2" and my jacket-style BCD, albeit nice, is a bit on the edge for that). My OMS backplate suits me better and is actually more comfortable on my back.
Plus BP/Ws harnesses are extremely adjustable and can give a good, snug fit to anyone.
Not all backplates are the same, the Dive Rite hurts my back while the OMS is just perfect, this is personal and up to one's frame, the point is : try it (loaded with a tank) before buying and check the comfort. Despite its "crude" appearance, a suitable stainless steel backplate, without any padding, can be (and often is) more comfortable than a padded, traditional BCD. At least that's my experience. And one will need 6 to 8 pounds less lead with a BP/W.
There are special weight pockets available for BP/W harnesses. No need for a weight belt.
There are many brands of BP/Ws around, some of them available in the UK, some of them likely to be ordered from the USA (Dive Rite, OMS, Halcyon, Oxycheq, Deep Sea Supply, etc). Personally, I own an OMS backplate with an Oxycheq Mach V wing, but other choices are obviously possible.
