I ran my positive cable from the starter to the pass fender well, connected the ignition power cable there and ran the length down along the pass side brake line route since there's a nice gap to fit it under the oem plastic cover. This runs to the spare tire well where my battery is hiding. It's grounded by the original ground cable on the rear frame rail using an exhaust mount bolt to ground it to the rail. I have no starting issues. As long as both cables are the appropriate gauge you shouldn't have any issues.
Cheers, JBrobst
"A life spent making mistakes is not only more honorable, but more useful than a life spent doing nothing." George Bernard Shaw