I don't know too much about the BB and its
rta capacities. There may be an insert or something to block off airflow to one coil, but I certainly haven't heard too much talk about it....
Is there a reason you want to run a single coil, and if this is your first stab at an
rta, I'd probably recommend getting a single coil deck that's somewhat large. There are some nice ones that make for great starters... The Hussar Coppervape clone is said to be better than the original, and it's pretty flexible. You can get it with various options, like single or dual coil deck, increased airflow, and it has some nice size options. It's the first deck I built and I really like it (especially now that I'm learning to wick better) and different
tank options too. It can be had for about $13 IIRC from 3FVape and the quality of the build is excellent.
Plenty of other great RTA DL options as well.
Hope this helps even slightly but I'm sure you'll get a more definitive answer to your question.
Anna