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I also recall my old metal ramps sinking into asphalt. I also had them push from time to time and had to have a helper hold them in place. The metal ones simply suck.
Points #1 and #2 are unsuitable. The only place that is safe is the tow hook. I use a bicycle inner tube to not scratch the paint against the hydraulic jack. I've done it many time without issue. The tow hook is very thick.