Grounding on portable equipment

I am designing the electrical controls on a portable water storage unit. This will have a gas powered generator that will power electrical heaters and controls. Everything will be grounded to the generator but would this need to have a grounding rod that would be inserted when the system is in use?
This system is totally enclosed in a metal frame and is used outdoors.
FYI: This is a military project.
Thanks for the help.

A former employee learned the electricians trade in the US Marine Corps. They did drive a ground rod for generators, but they were trailer mounted, not what I envison as portable. (As an aside, he had a great anecdote about trying to explain to an officer why the standard ground rod wasn't being effective during Desert Storm deployment!)

NEC has a code for portable gensets and grounding that basically states the 2 conditions when its NOT necessary to use a ground rod.
1. The generator supplies only equipment mounted on the generator, cord and plug connected equipment thru receptacles mounted on the generator, or both, and.
2. The non current carrying metal parts of equipment and the equipment grounding conductor terminals are bonded to the generator frame.

When I was in the amusement business we used gensets to power midways at state and county fairs. Depending on where but in most cases I was required not to have just 1 but 3-10ft ground rods driven 8 ft deep and spaced no more than 10ft apart in a triangular arrangement.

I would recommend you drive at least one ground rod 8ft and see what happens if/when you may get inspected. Make sure the ground wire used is properly sized.

Genset Grounding

Grounding is require if a part of the electric network is grounded (such as generator NULL=Star neutral, or at load side).
In that case you have to drive grounding rods for the genset and for the load, connect a NULL grounding between the genset and the load, and connect all grounding wires to these NULL grounding point.
If the system is floating, usually a ground monitor unit is required by local codes and is also highly recomended, to alert when first ground fault path occurs.
Some systems, especially militarry, are sensitive to grounding current flowing around the equipment, and may require special consideration.