Make it so diesel only loads on traincar tanks and don’t make it lootable like the old diesel. Make it behave like water does. You’ll have to pump it between fuel tanks.
So you get your traincar full of diesel to trainyard. Only you also need to have a waiting vehicle with the fuel tank vehicle module to transfer the diesel fuel into.
Next the vehicle gets driven over to excavator where the fuel gets tranfered again and will be able to run the monument.
This has some cool potential to get vehicles more action.