From the information provided, I don’t know if the power at the pole comes directly from a utility or from a main service panel located elsewhere. If the power is from a utility, then the NEC requires an earth ground, e.g., grounding rods, at the service panel. If power comes from a main service panel located elsewhere, then there are two alternatives. One is to run a separate ground wire from the main panel to the subpanel and keep the ground and neutral wires separate in the subpanel. The other way, permitted in some jurisdictions, is to put in ground rods at the subpanel and bond the ground and neutral together at the subpanel. The NEC prohibits a neutral-ground connection in a subpanel without establishing a new ground because the current flowing through the neutral back to the main service panel can create a shock hazard and power quality problems.
This should be evaluated by a qualified electrician or perhaps a building inspector. A building inspector will answer any specific questions and ensure that the wiring meets the local building codes. Following the building codes makes it much safer.
2015 Wildcat 282 RKX
2011 F350 Lariat, 6.7 L. Diesel, 8 ft., SRW, Reese R20