For everyone who looks at Sparkfun for stuff … please note that their PCB’s use about the lowest weight copper I have ever seen! I have had many of their boards delaminate the traces while trying to solder components. Granted they have some neat stuff … but it is HOBBY grade at best. If you like one of their circuit designs, they have the files online … snag the file … modifiy the trace widths or get the boards made with more than whatever tiny oz weight they are using and go for it.
You can use PCBs for high current. I had to make a replacement board design for the Atari Hercules pinball machine which used Que balls for pinballs … want current? The flipper circuits on this thing was hideous. 3 Oz copper board and wide traces did the trick.
Control lines from top side to control power is simple enough. If you want to use something that is specifically made for controlling high current DC … check out Crydom’s site. http://www.crydom.com/en/
I use their products on high current heater applications at work and for my surface mount reflow oven at home. Sweet, simple and last forever.