i need to replace my battery with a bigger deep cycle battery but it wont fit in my civic...my question is if i want to put it in my trunk should i simply extend the power wire to the trunk and make a new ground close to the battery, or would there be too much resistance in the longer wire?

 

iwhat you said is fine, no matter where you put it the ground will always have resistance

 

Why not get a deep cycle from SVR? Fits with zero modification....