Mounting the Flat Holder of the last page on a transparent Spider is the ultimate solution for Newtonian Telescopes.  In 1958 I conceived of a Transparent Spider consisting of a Neutral Corrector Plate that would hold the secondary the same way a Schmidt corrector Plate holds its Secondary Mirror.  That was my first Telescope, and I was heavily advised against it.  With the advent of the new Schmidt Newtonian and Maksutov Newtonian telescope designs, this possibility has already been considered by others.
In fact, a newer Cassegrain design for Maksutov Cassegrain telescopes employing a thinner "Neutral Corrector Plate" holding a smaller diameter traditional Maksutov Corrector Plate in the central area of the incoming light path has been successfully used.  This proves the value of the "Neutral Corrector Plate", and reveals the arguments against using such a corrector plate are groundless.  Thus I see no reason not to implement the Neutral Corrector Plate as a "Transparent Spider".   Traditional Spiders produce a pair of visible spikes for each vane. While these spikes do not affect the telescope's Wavefront Error, they are annoying.  Recent spider designs have employed curved vanes to spread the spikes over a wider area, - diminishing their visibility but failing to eliminate them as a Transparent Spider would.