you can use 2 pumps in the back,
but here are the limitations of going with 2 pumps in the back instead of a koralia in the front .......
1. the flow is unidirectional that is even though there is good flow over all there would be two jets like flow streams making it too much flow to keep any corals in their way and may cause sand storms or remove sand from the place they are hitting.
2. the overflows of nuvo tanks are very calculated i think. .so if you stuff too much filter floss or anything limiting the flow the main display area will overflow as the back chamber would be emptied much faster.
having said that, there is no rule that flow has to be done only in one way .. wait till you need more flow after you add corals and then decide what to do would be my suggestion ..