Like you I am currently RTITB certified but joined iTRUK as well so I could train people to operate safely but to a work standard rather than "test standard".
You could consider using plastic pipe to create the barriers. Would need the fittings to hold them upright and then horizontal and could have it high enough so that it moves if touched by the truck. Means an initial outlay but its waterproof and easy to move.
Good luck with the training.