[DonC]

If the battery is in good shape and of a proper Cold Cranking Amps value having it in the trunk should not effect the engines ability to start.
My ERA has the battery in the trunk with the cables routed along the frame members and has never experienced a problem. ERA offers the trunk mounted battery as a regular option and I'm quite pleased with it.
Using an Optima or other sealed battery is very good advice since venting is an issue with conventional batteries.
DonC