The sweetest mechanical advantage is a rotary hammer, nickname Macho Drill for a reason, that's what the guys that set trailers use. Will blast an anchor right through six inches of asphalt and underlayment like it was butter. If you can borrow one of these and find an anchor with a head setup for, or driver attachment to adapt to your anchor, it's the way to go. The alternative, like Jerome said is a tire tool or long piece of pipe or rod for a cheater bar. If the ground is hard, get your anchor started, pour a 32 ounce cup of water on it, wait a minute, twist some more and repeat if necessary.