EricStrong

Dimensions & weight: 13 in H x 29 in W x 17 in D (33.02 m H x 73.66 cm W x 43.18 cm D) Weight: 53 lbs (24.04 kg)... Not so big. useful thing in a garage )

Well as a minimum, this crossover wagon will have enough place to install a good audio amplifier with big-big speakers! ))

You don't need to cut your tray, Your car (2015 Ford Fusion) needs a group 48 battery so you can buy for example ACDelco 48AGM - Cold Cranking Amps (CCA): 760, Reserve Capacity (RC): 120, Amp-Hours (AH): 70. It has a warranty for 36 months. Here's battery comparison details: https://batterygroupexpert.com/best-car-battery/ You looked to the Optima D35 Yellow Top Deep Cycle Battery, Group Size 35, 620 CCA - I think it is the wrong battery group for your car, and CCA is too small