aftermarket audio ideas

Ok here goes, will my 04 prius blow burn short out or slap me in a bad place if I put a small deep cycle battery(stinger sp800) in the rear, put a battery isolater(a big diode) on it connect it to the backup 12 volt in the rear with 8 awg cable and put a 30 amp fuse inline(was told by toyota tech that i would be able to draw 30 amps of current safely with non jbl radio), and then use deep cycle batt to power a 5 channel amplifier that pulls 60 amps of current(alpine mrvf450) and an aftermarket radio(alpine cda9835) which pulls 10 amps. if any one has any other suggestions warnings, rude awakenings, or if someones got enough money to burn try it out for me. thx.