If the rock is totally cured and there is no exposuer in (stays wet and near same tempurture)transport any amount would be OK without a spike........ There would be no die to cause one. But be sure the rocks you pick are totally cured before doing so.
On the other hand if your tank has a fair amount of LR now, adding base rock would work just as well.....the beneficial bacteria etc in your existing rocks will soon begin to inhabit the new base stuff, for far less cost...... Only immediate down side is the lack of coralline coverage on the base till some time passes.