The engine and transmisson should be plenty of weight up front. Moving your battery to the trunk shouldn't cause you to lose traction. If you are building a car for hard acceleration, you probably have a great suspension and don't have to worry about weight transfer. If after installing a good suspension, you are getting traction problems, I would have to say that you need tires that are made for ultra traction or sport (Falken's, Pirelli's, Nitto's) and not for comfort or treadwear(Michelins, Toyo's, Continentals).
As for the battery relocation issue. I used 2 guage wire and just extended the positive and negative battery wire all the way to the trunk. No problems at all so far, works like a charm. The first time I did it, I used wire that was too thin and it would take a few seconds to turn the ignition over, but it always started. The resistance was too high when trying to start the car so I bought thicker wire and it works great now.