I personally prefer things to work with the least amount of iron-fist rules.
In my preferred paradigm, a game trying to replicate movie action would be a scenario... Plenty of neutrals helping the rebels-without-a-homeworld (just a hidden, tiny ice world colony for maintaining political contact?) all while trying to avoid the planetbusting wrath of the established empire empire (who starts with subjugation treaties with everyone, and thus huge resources for huge ships and fleets with which to oppress the others).
The scenario would start out with a big fleet of movie like designs, but there would be no reason you couldn't build new custom stuff when events start unfolding.
Maybe the rebels could start out with a single million-organics cost fighter that has a special damage type, Deathstar-killer weapon (only planet destroyers, 64k damage?)
Try to keep it from dying before the final battle...
On the other hand, for a typical PBW game, you're starting your own empires from scratch, and you have 5 or 6 equally strong empires. Too much canon starts to conflict with the actual game events in that case
PS:
Certainly, going with a heavy handed canon approach will be the most straightforward.
Plug in a limited set of options, and set the abilities such that all of the legal tokens are reasonably accurate.
Making it work sandbox style takes a lot more planning, math, effort, more math, planning, and tuning. And free time to do all of that.