That 8x6 one looks perfect! Thumb's up, indeed!
Nice picture, by the way.
I've been considering all the iterations of M-, B+, and B-, with one sided and 2 sided pcb.
On the power board, you can do
M-, B+, B-
M-, B-, B+,
B+, M-, B-.
Each choice has it's pros and cons, but the best way, it seems to me, is
B+, M-, B-. The smaller version was M-, B-, B+, which makes it easier to connect the capacitors, but needed those red wires,
picture making it totally unacceptable in the high power case. Well, there are other possibilities, but B+, M-, B- seems to be the best.