I use to run an EOS as second box. Now I just run two machs or a Vargur + Mach. It’s hectic, but very quick.
Dominix are easy to train, but move painfully slow. Usually they are run in a RR setup.
Unless you’re going for a tinker RS setup, I’d train for a different ship/skillset. Projectile instead of missiles, or a T3 for cloaky operation. Or a Stratios can be effective for up to DED 5.