Decks, Patios, Porches and Docks - Outdoor wood stair building question

Our property has a slope on one side, about 6 ft. high and 8-10 ft. on the diagonal. We are filling it in with wintercreeper and juniper, but are leaving a space for steps to get up and down the slope. So unlike most available plans which show the steps being built on to a deck or porch, these steps will simply end at the top of the slope. So I would like some options regarding how best to anchor them. I prefer not to pour concrete footings, although will if that is the only realistic option. What about this -- bolting 4x4's between the stringers and securing them in the ground with 30 in. landscape timber stakes? Any problems with this, assuming I can drive them in that deeply?

I usually use 6x6 timbers and dig out two steps at a time, laying a long 6x6 to cover the length of the two steps, then step in 11 inches and attach another 6x6 (the length of two steps) on top and secure with Timberlocks (10"). Between the steps stringers, I install 6x6's to use as actual step treads and bolt them from the side with the Timberlocks. When you finish you can backfill against the stringers. You won't have to drive any rebar, etc because by cross bolting them, the entire set of steps becomes one unit.

Another option may be to use something like keystone or garden wall blocks to form your steps with. Google "Basalite" (the mfgr. of thiese blocks) and see what you find.