Continuing the thread of your idea, it is possible that this platform belongs to a causeway originally planned for Khufu's Ka pyramid and the so called trial passage was its under-belly. This pyramid was then abandoned and the Ka pyramid was instead built next to Henutsen's. The mortuary temple was expanded to honor Re and the causeway was built across the plot of where the pyramid would have stood.
This all ocurred because of a religious shift in year five. I was able to date an almost complete solar eclipse to Khufu's reign and adked Zahi Hawass if the "fifth" year meant five or ten and Zahi thought probably ten. I cannot do this from where I am but Spiros can.
Intuitively you picked up on the planning confusion caused by these changes. There is no rhyme or reason because plans changed. Whatever theory one models I think must incorporate this idea of a deviation from the original plan and I think this deviation in one era can be confused with building in two different eras. Yes two eras may still be possible but one should formulate predictions to see if one can test these alternatives against each other.
I agree with the NW logistical access. I looked at Dassaults contour maps again yesterday and it practically jumps at you as the most logical choice because it is smooth way up. I know because I walk that way every time I visit Giza as do Millions of tourists. Therefore, the causeway and this remnant, if it is from that time, had some other function and symbolism is on the table. For example a solar boat ramp for the festival of Sokar.