TT, one of our proposals was for a palletised FRL centreline hose unit. Additional cargo bay tanks could be RORO, but would be essential if the KC390 was to have any worthwhile functionality as a multi-role aircraft.
Quite how Embraer would fit a boom system plus operator station remains to be seen, but would probably remove any useful air transprt capability due to the level of rear ramp modification needed. The added weight would also increase the ZFW, further limiting AAR fuel offload capacity.