its ok to have capacitors no matter wat people said.
reasons why:
i always had excellent experience installin caps
it will help voltage drops
it will not take alot of power like a batterie and it will not make your alternator work harder and makin a new load since the cap will charge fast as hell while the amp is at idle pulling around 10 amps at idle.
it will not take power from your engine,
if u dont wanna buy alternator, get a 5 farad capacitor even if u overexcceded the rule of thump of the caps, do the big 3 or upgrade your batterie cables, and alternator cables