Where should heavy passenger suitcases and freight items be stowed inside the underfloor luggage compartments of a touring coach?

1. Low down and evenly distributed between the axles near the centre of the vehicle
2. Stacked high on top of soft bags near the luggage compartment ceiling
3. Concentrated entirely in the rearmost overhang compartment behind the drive axle
4. Stacked in the front entrance stepwell