Wiring question.

[Gravy]

For the car, i've got a new batery in the car, and today i found out that the terminals are a little two high and are rubbing against the hood's heat shield, and now getting in the hood. So, instead of doing the easy thing, and getting a new battery that's the right size, i'm doing a battery relocate to he rear trunk.There's a 2 guage wire for a sub system, no longer in use, that i will use for the power line, there is an inline fuse. So that's covered but there's no ground running to the rear, it's grounded out onto the chasis in the rear. Does anyone thing i should run a negative ground from the front ground wires to the rear, or just make sure it's a good ground in the rear and let it go from there?