Keep it simple stupid.
And I'd build it for five lines. You can leave some blank, but having extra holes can be convienent.
Fuel supply
Fuel return
Left brake fluid feed line
Right brake fluid feed line
Wiring for rear lights, fuel pump.
Some (most) won't need or want two brake lines, but the guys who might buy this bracket are also the guys who are more likely to have cutting brakes.
Make the 'wiring' location larger. Some guys go so far as to run two fuel pumps, rear electric radiators fans, and who knows what else.