Nobody gets the prize...
Startracks makes Xplorer and Leisure Travel VansSomewhere, they say they will customize the Serenity van for you.
Turtle Top can customize a Titan-like rig for you.
These two (and the small Coach House Platinum) are the most pure B+ rigs I can think of. They all three come from companies that specialized only in Class B campervans, but saw the need to produce B-Plus rigs.
Since you can get Startracks and Turtle Top to do a custom B+ van for you, they are the first I can identify as producers of PLCs (Personal Low-profile class C) motorhomes.
On Edit: I must not forget Dodgen Industries, who make Born Free Motorcoaches, and who also say they will customize for you.
So there are three sources for a PLC.
We need another subforum:B