That is correct. Although I would prefer to use only 2 packs just to limit the number of connections and wires. I use the same brand, capacity and "C" rating. No worries. If you know how your physical layout will be you can make the wires as short as possible as well. I use 5.5 mm bullets on all my bigger packs so it is very easy to do this. 3 packs using dean's is a bit tougher, but you can still do it.

MPI makes a harness:

http://www.maxxprod.com/mpi/mpi-21.html#Harness