Blackley Unit

On a job at the moment were the client wants a 63 amp three phase blackley unit installed (it will be buried in the ground in a field). the unit is a large metal box with a hinged lid with an adaptable box inside. The adaptable box houses a 63 amp three phase breaker which feeds a 63 amp commando socket. The blackley unit has no IP seal on it at all and a massive hole in the bottom, the commando socket is IP 66 and the adaptable box is IP 55, and there is no rcd or rcbo protection in the unit.
The consultant is insisting that the unit does not need to be rcd protected which I completely disagree with, as the client will only be plugging in a consumer unit to feed their equipment and that consumer unit will be rcd protected. This means that the unit will be unprotected and also the cable feeding the unit as well as he doesn't want an rcd at the origin of the circuit either.
The blackly unit is about 100 mts away from the panel board. In the regs it says about rcd'ing socket outlets that are taken away from the equipotential zone but he's having none of it. What are your thoughts?