Hi, distinguish three types of grounding:
1/ RF ground. You do not need any with a dipole and QRP. Moreover, a
spike in the soil a VERY poor RF grounding. Avoid ground plane and
other antennas, requiring a huge radial system as an RF ground, for
temporary installations. (There is one exception: 2 - 3 radials
running directly into sea water are enough if you work on an ocean
beach. A vertical is a perfect DX antenna in this case.)
2/ Lightning protection. You do not need any for portable operation.
If a storm approaches, pack you equipment and leave the park. It is
the best lightning protection not to be there :-)
3/ Static bleeding. It is a good idea to give the static in the dipole
a ground path. The spike in the ground is O.K. for this
purpose.Connect the case of your TRX to it by a thick, short, stranded
wire.

73 Ivan OK1SIP