Well... No, you can't. You need a 5th Empire toon at 7* to try. That being said, if you'll get your stormtrooper in time, EP should make it easy. If your only use for the Empire is R2, than you're good to go. But find a use for the Empire and gear then up more.
Actually, after the EP rework, each turn the rebels take works against them... With the 20% max health damage at the start of each turn, it'll be over before they know it.
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Other than to finish Storm trooper to gear viii and 7 star and finish off the non omega non zeta abilities on everyone I'd say you are fine.
depends on your mods and RNG really