Like all things with an entire industry dedicated to it, there are tons of different opinions and options. My "I'm-going-all-in" paint job layering is: epoxy primer, body filler, another coat of epoxy to seal any bare spots, high build primer, then some type of sealer (usually thin out epoxy primer with acetone), then base and clear.
That being said if you're not using super expensive paint it may not be worth the extra steps. When you have $600-800 in paint or a ton of time in body work or stripes etc. it becomes more worth it to cover your ass. Ideally you want to seal all metal with a direct to metal primer, if the bare metal spots are small you can usually get away with skipping that.
This thing is going to be a real class act with black and pin stripes. are you hand painting the stripes or doing them with tape?