The width of the steel is irrelevant. The thickness is. At 0.5" and 8' length, the slenderness ratio would kill you UNLESS you were able to support the steel continuously along its length while being inserted (by any means) into the ground.
My question back to you - what does the truck have to do with the question? I can weld an 8' length of steel to the nose of a B-1 and power-dive it into the ground. The steel rod and everything else would probably be 8' or more beneath the finish grade.
The sad thing is that your solution would be more cost-effective that the WOD as currently practiced.
Boring contractors bore hundreds of feet under anything these days for with a 1-1/4 (+/-)rod and aim it as well.