I am assuming that you have 2 amps...
In light of that, you might be beter to do this :

All 4 outs respectively to your 4 channel amp, pass through that amp to the sub amp,
use the (rockford sub amp) bass control to adjust gain on subs.
If you can't do this, (pass through), then stick with what you've described.
run the front out on empeg to all 4 speakers and rear to the subs.
that way there you dont have to send bass to rear speakers